From 76ece98351ece90df9df2f0db0c1471bf46d574a Mon Sep 17 00:00:00 2001
From: Jed <gitea@jedarden.com>
Date: Wed, 13 Apr 2022 11:59:45 -0400
Subject: [PATCH] Update advent of code

---
 2021/22-1.py  |  83 +++++
 2021/22.input | 420 ++++++++++++++++++++++
 2021/22.py    |  74 ++++
 2021/22.test  |   4 +
 2021/23.input |   7 +
 2021/23.py    | 963 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2021/23.rs    | 164 +++++++++
 2021/23.test  |  23 ++
 2021/24.input | 252 +++++++++++++
 2021/24.py    |  99 ++++++
 2021/24.test  |   0
 2021/25.input | 137 +++++++
 2021/25.py    |  49 +++
 2021/25.test  |   9 +
 14 files changed, 2284 insertions(+)
 create mode 100644 2021/22-1.py
 create mode 100644 2021/22.input
 create mode 100644 2021/22.py
 create mode 100644 2021/22.test
 create mode 100644 2021/23.input
 create mode 100644 2021/23.py
 create mode 100644 2021/23.rs
 create mode 100644 2021/23.test
 create mode 100644 2021/24.input
 create mode 100644 2021/24.py
 create mode 100644 2021/24.test
 create mode 100644 2021/25.input
 create mode 100644 2021/25.py
 create mode 100644 2021/25.test

diff --git a/2021/22-1.py b/2021/22-1.py
new file mode 100644
index 0000000..6e042b1
--- /dev/null
+++ b/2021/22-1.py
@@ -0,0 +1,83 @@
+def parse_input(s):
+    for line in s.splitlines():
+        state, rest = line.split()
+        x, y, z = rest.split(',')
+        x0, x1 = x[2:].split('..')
+        xrange = range(int(x0), int(x1)+1)
+        y0, y1 = y[2:].split('..')
+        yrange = range(int(y0), int(y1)+1)
+        z0, z1 = z[2:].split('..')
+        zrange = range(int(z0), int(z1)+1)
+
+        yield state, xrange, yrange, zrange
+
+def get_subrange(crange, low, high):
+    c0 = crange[0]
+    c1 = crange[-1]
+    if c1 < low:
+        return []
+    elif c0 > high:
+        return []
+    c0 = max(c0, low)
+    c1 = max(c1, low)
+    c0 = min(c0, high)
+    c1 = min(c1, high)
+    return range(c0, c1+1)
+
+def part1(s):
+    data = list(parse_input(s))
+
+    cubes = {}
+    for idx, item in enumerate(data):
+        state, xr, yr, zr = item
+        for x in get_subrange(xr, -50, 50):
+            for y in get_subrange(yr, -50, 50):
+                for z in get_subrange(zr, -50, 50):
+                    cubes[x,y,z] = state
+
+    answer = sum(1 for s in cubes.values() if s == 'on')
+
+    print(f'The answer to part one is {answer}')
+
+def count_uninterrupted(item, rest):
+    _, xr, yr, zr = item
+    total = len(xr) * len(yr) * len(zr)
+
+    conflicts = []
+    ref_val = 0
+
+    for item in rest:
+        state, xr2, yr2, zr2 = item
+
+        cxr = get_subrange(xr2, xr[0], xr[-1])
+        cyr = get_subrange(yr2, yr[0], yr[-1])
+        czr = get_subrange(zr2, zr[0], zr[-1])
+
+        if len(cxr) == 0 or len(cyr) == 0 or len(czr) == 0:
+            continue
+
+        conflicts.append((state, cxr, cyr, czr))
+        ref_val += len(cxr) * len(cyr) * len(czr)
+
+    for idx, item in enumerate(conflicts):
+        total -= count_uninterrupted(item, conflicts[idx+1:])
+
+    return total
+
+def part2(s):
+    data = list(parse_input(s))
+
+    answer = 0
+
+    for idx, item in enumerate(data):
+        state, xr, yr, zr = item
+        if state == 'off':
+            continue
+        answer += count_uninterrupted(item, data[idx+1:])
+
+    print(f'The answer to part two is {answer}')
+
+with open("./2021/22.input") as input_file:
+    INPUT = input_file.read()
+part1(INPUT)
+part2(INPUT)
\ No newline at end of file
diff --git a/2021/22.input b/2021/22.input
new file mode 100644
index 0000000..bf36ef9
--- /dev/null
+++ b/2021/22.input
@@ -0,0 +1,420 @@
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+on x=-33152..52,y=-93382..-74489,z=-32975..15
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+on x=61402..80219,y=4975..20655,z=-18161..1814
+on x=-63528..-40613,y=-54656..-51615,z=-18568..-7770
+off x=21952..44859,y=28549..43996,z=-67616..-44529
+off x=349..11389,y=34235..65301,z=-69339..-52128
+off x=27055..34708,y=-14438..8061,z=68787..74936
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+on x=53378..65013,y=1739..17704,z=43369..64000
+on x=-21771..369,y=56025..64514,z=46505..57641
+off x=-3256..15577,y=8710..41297,z=65810..87150
+on x=54452..90336,y=-44681..-27689,z=-3182..19982
+off x=55359..89314,y=25058..37589,z=-28802..-8718
\ No newline at end of file
diff --git a/2021/22.py b/2021/22.py
new file mode 100644
index 0000000..efe6d03
--- /dev/null
+++ b/2021/22.py
@@ -0,0 +1,74 @@
+# with open("./2021/22.test") as input_file:
+with open("./2021/22.input") as input_file:
+    input_data = input_file.read()
+
+instructions_raw = input_data.split("\n")
+
+print(instructions_raw)
+
+instructions_parsed = []
+for one_instruction in instructions_raw:
+    one_parsed = {}
+    one_parsed['instruction'] = one_instruction.split(" ")[0]
+    one_parsed['x_min'] = int(one_instruction.split(" ")[1].split(",")[0].split('=')[1].split('..')[0])
+    one_parsed['x_max'] = int(one_instruction.split(" ")[1].split(",")[0].split('=')[1].split('..')[1])
+    one_parsed['y_min'] = int(one_instruction.split(" ")[1].split(",")[1].split('=')[1].split('..')[0])
+    one_parsed['y_max'] = int(one_instruction.split(" ")[1].split(",")[1].split('=')[1].split('..')[1])
+    one_parsed['z_min'] = int(one_instruction.split(" ")[1].split(",")[2].split('=')[1].split('..')[0])
+    one_parsed['z_max'] = int(one_instruction.split(" ")[1].split(",")[2].split('=')[1].split('..')[1])
+
+    print(one_parsed)
+
+    instructions_parsed.append(one_parsed)
+
+on_counter = 0
+on_array = {}
+for one_instruction in instructions_parsed:
+    print(one_instruction)
+    instruction_counter = 0
+
+    x_min = one_instruction['x_min']
+    x_max = one_instruction['x_max']
+    y_min = one_instruction['y_min']
+    y_max = one_instruction['y_max']
+    z_min = one_instruction['z_min']
+    z_max = one_instruction['z_max']
+
+    # # Constrain to -50..50
+    # x_min = max(one_instruction['x_min'], -50)
+    # x_max = min(one_instruction['x_max'], 50)
+    # y_min = max(one_instruction['y_min'], -50)
+    # y_max = min(one_instruction['y_max'], 50)
+    # z_min = max(one_instruction['z_min'], -50)
+    # z_max = min(one_instruction['z_max'], 50)
+
+    for x in range(x_min, x_max + 1):
+        for y in range(y_min, y_max + 1):
+            for z in range(z_min, z_max + 1):
+                if x not in on_array.keys():
+                    on_array[x] = {}
+                if y not in on_array[x].keys():
+                    on_array[x][y] = {}
+                if z not in on_array[x][y].keys():
+                    on_array[x][y][z] = ""
+                
+                if one_instruction['instruction'] == 'on' and on_array[x][y][z] != 'on':
+                    on_counter += 1
+                    instruction_counter += 1
+                if one_instruction['instruction'] == 'off' and on_array[x][y][z] == 'on':
+                    on_counter -= 1
+                    instruction_counter -= 1
+                on_array[x][y][z] = one_instruction['instruction']
+                print(f'''Processing ({x:6}, {y:6}, {z:6}) {on_counter:6}''', end="\r")
+    print("\r", instruction_counter)
+# on_counter = 0
+# for x in on_array.keys():
+#     for y in on_array[x].keys():
+#         for z in on_array[x][y][z].keys():
+#             print(f'''Counting ({x:6}, {y:6}, {z:6})''', end="\r")
+#             on_counter += 1
+
+print(on_counter)
+
+
+
diff --git a/2021/22.test b/2021/22.test
new file mode 100644
index 0000000..4d036d6
--- /dev/null
+++ b/2021/22.test
@@ -0,0 +1,4 @@
+on x=10..12,y=10..12,z=10..12
+on x=11..13,y=11..13,z=11..13
+off x=9..11,y=9..11,z=9..11
+on x=10..10,y=10..10,z=10..10
\ No newline at end of file
diff --git a/2021/23.input b/2021/23.input
new file mode 100644
index 0000000..e97924a
--- /dev/null
+++ b/2021/23.input
@@ -0,0 +1,7 @@
+#############
+#...........#
+###C#A#B#D###
+  #D#C#B#A#
+  #D#B#A#C#
+  #B#A#D#C#
+  #########
\ No newline at end of file
diff --git a/2021/23.py b/2021/23.py
new file mode 100644
index 0000000..da1dbb0
--- /dev/null
+++ b/2021/23.py
@@ -0,0 +1,963 @@
+#region Imports
+import collections
+import copy
+import functools
+import heapq
+import itertools
+import math
+import operator
+import re
+import sys
+import typing
+from collections import Counter, defaultdict, deque
+from copy import deepcopy
+from functools import reduce
+from pprint import pprint
+#endregion
+
+sys.setrecursionlimit(100000)
+T = typing.TypeVar("T")
+# Copy a function if you need to modify it.
+
+AIR = "."
+WALL = "#"
+
+#region Strings, lists, dicts
+def lmap(func, *iterables):
+    return list(map(func, *iterables))
+def make_grid(*dimensions: typing.List[int], fill=None):
+    "Returns a grid such that 'dimensions' is juuust out of bounds."
+    if len(dimensions) == 1:
+        return [fill for _ in range(dimensions[0])]
+    next_down = make_grid(*dimensions[1:], fill=fill)
+    return [copy.deepcopy(next_down) for _ in range(dimensions[0])]
+def min_max(l):
+    return min(l), max(l)
+def max_minus_min(l):
+    return max(l) - min(l)
+def partial_sum(l):
+    "out[i] == sum(in[:i])"
+    out = [0]
+    for i in l:
+        out.append(out[-1] + i)
+    return out
+cum_sum = partial_sum
+def list_diff(x):
+    return [b-a for a, b in zip(x, x[1:])]
+def flatten(l):
+    return [i for x in l for i in x]
+def every_n(l,n):
+    return list(zip(*[iter(l)]*n))
+def windows(l, n):
+    return list(zip(*[l[i:] for i in range(n)]))
+
+def ints(s: str) -> typing.List[int]:
+    assert isinstance(s, str), f"you passed in a {type(s)}!!!"
+    return lmap(int, re.findall(r"(?:(?<!\d)-)?\d+", s))  # thanks mserrano!
+def positive_ints(s: str) -> typing.List[int]:
+    assert isinstance(s, str), f"you passed in a {type(s)}!!!"
+    return lmap(int, re.findall(r"\d+", s))  # thanks mserrano!
+def floats(s: str) -> typing.List[float]:
+    assert isinstance(s, str), f"you passed in a {type(s)}!!!"
+    return lmap(float, re.findall(r"-?\d+(?:\.\d+)?", s))
+def positive_floats(s: str) -> typing.List[float]:
+    assert isinstance(s, str), f"you passed in a {type(s)}!!!"
+    return lmap(float, re.findall(r"\d+(?:\.\d+)?", s))
+def words(s: str) -> typing.List[str]:
+    assert isinstance(s, str), f"you passed in a {type(s)}!!!"
+    return re.findall(r"[a-zA-Z]+", s)
+
+def keyvalues(d):
+    return list(d.items())  # keep on forgetting this...
+def make_hashable(l):
+    if isinstance(l, list):
+        return tuple(map(make_hashable, l))
+    if isinstance(l, dict):
+        l = set(l.items())
+    if isinstance(l, set):
+        return frozenset(map(make_hashable, l))
+    return l
+def invert_dict(d, single=True):
+    out = {}
+    if single:
+        for k, v in d.items():
+            v = make_hashable(v)
+            if v in out:
+                print("[invert_dict] WARNING WARNING: duplicate key", v)
+            out[v] = k
+    else:
+        for k, v in d.items():
+            v = make_hashable(v)
+            out.setdefault(v, []).append(k)
+    return out
+#endregion
+
+#region Algorithms
+class RepeatingSequence:
+    def __init__(self, generator, to_hashable=lambda x: x):
+        """
+        generator should yield the things in the sequence.
+        to_hashable should be used if things aren't nicely hashable.
+        """
+        self.index_to_result = []
+        self.hashable_to_index = dict()
+        for i, result in enumerate(generator):
+            self.index_to_result.append(result)
+            hashable = to_hashable(result)
+            if hashable in self.hashable_to_index:
+                break
+            else:
+                self.hashable_to_index[hashable] = i
+        else:
+            raise Exception("generator terminated without repeat")
+        self.cycle_begin = self.hashable_to_index[hashable]
+        self.cycle_end = i
+        self.cycle_length = self.cycle_end - self.cycle_begin
+
+        self.first_repeated_result = self.index_to_result[self.cycle_begin]
+        self.second_repeated_result = self.index_to_result[self.cycle_end]
+    
+    def cycle_number(self, index):
+        """
+        Returns which 0-indexed cycle index appears in.
+        cycle_number(cycle_begin) is the first index to return 0,
+        cycle_number(cycle_end)   is the first index to return 1,
+        and so on.
+        """
+        if index < self.cycle_begin:
+            print("WARNING: Index is before cycle!!")
+            return 0
+        return (index - self.cycle_begin) // self.cycle_length
+
+    def __getitem__(self, index):
+        """
+        Gets an item in the sequence.
+        If index >= cycle_length, returns the items from the first occurrence
+        of the cycle.
+        Use first_repeated_result and second_repeated_result if needed.
+        """
+        if index < 0:
+            raise Exception("index can't be negative")
+        if index < self.cycle_begin:
+            return self.index_to_result[index]
+        cycle_offset = (index - self.cycle_begin) % self.cycle_length
+        return self.index_to_result[self.cycle_begin + cycle_offset]
+
+def bisect(f, lo=0, hi=None, eps=1e-9):
+    """
+    Returns a value x such that f(x) is true.
+    Based on the values of f at lo and hi.
+    Assert that f(lo) != f(hi).
+    """
+    lo_bool = f(lo)
+    if hi is None:
+        offset = 1
+        while f(lo+offset) == lo_bool:
+            offset *= 2
+        hi = lo + offset
+    else:
+        assert f(hi) != lo_bool
+    while hi - lo > eps:
+        mid = (hi + lo) / 2
+        if f(mid) == lo_bool:
+            lo = mid
+        else:
+            hi = mid
+    if lo_bool:
+        return lo
+    else:
+        return hi
+
+def binary_search(f, lo=0, hi=None):
+    """
+    Returns a value x such that f(x) is true.
+    Based on the values of f at lo and hi.
+    Assert that f(lo) != f(hi).
+    """
+    lo_bool = f(lo)
+    if hi is None:
+        offset = 1
+        while f(lo+offset) == lo_bool:
+            offset *= 2
+        hi = lo + offset
+    else:
+        assert f(hi) != lo_bool
+    best_so_far = lo if lo_bool else hi
+    while lo <= hi:
+        mid = (hi + lo) // 2
+        result = f(mid)
+        if result:
+            best_so_far = mid
+        if result == lo_bool:
+            lo = mid + 1
+        else:
+            hi = mid - 1
+    return best_so_far
+
+# Graphs
+def topsort(out_edges: typing.Dict[T, typing.List[T]]) -> typing.List[T]:
+    temp = set()  # type: typing.Set[T]
+    seen = set()  # type: typing.Set[T]
+    out = []
+
+    def dfs(n):
+        nonlocal temp,seen,out
+        if n in seen:
+            return
+        if n in temp:
+            raise Exception("not a DAG")
+        temp.add(n)
+        if n in out_edges:
+            for other in out_edges[n]:
+                dfs(other)
+        temp.remove(n)
+        seen.add(n)
+        out.append(n)
+    
+    for n in out_edges:
+        dfs(n)
+    out.reverse()
+    return out
+
+
+def path_from_parents(parents: typing.Dict[T, T], end: T) -> typing.List[T]:
+    out = [end]
+    while out[-1] in parents:
+        out.append(parents[out[-1]])
+    out.reverse()
+    return out
+
+
+def dijkstra(
+    from_node: T,
+    expand: typing.Callable[[T], typing.Iterable[typing.Tuple[int, T]]],
+    to_node: typing.Optional[T] = None,
+    heuristic: typing.Optional[typing.Callable[[T], int]] = None,
+) -> typing.Tuple[typing.Dict[T, int], typing.Dict[T, T]]:
+    """
+    expand should return an iterable of (dist, successor node) tuples.
+    Returns (distances, parents).
+    Use path_from_parents(parents, node) to get a path.
+    """
+    if heuristic is None:
+        heuristic = lambda _: 0
+    seen = set()  # type: typing.Set[T]
+    g_values = {from_node: 0}  # type: typing.Dict[T, int]
+    parents = {}  # type: typing.Dict[T, T]
+
+    # (f, g, n)
+    todo = [(0 + heuristic(from_node), 0, from_node)]  # type: typing.List[typing.Tuple[int, int, T]]
+
+    while todo:
+        f, g, node = heapq.heappop(todo)
+
+        assert node in g_values
+        assert g_values[node] <= g
+
+        if node in seen:
+            continue
+
+        assert g_values[node] == g
+        if to_node is not None and node == to_node:
+            break
+        seen.add(node)
+
+        for cost, new_node in expand(node):
+            new_g = g + cost
+            if new_node not in g_values or new_g < g_values[new_node]:
+                parents[new_node] = node
+                g_values[new_node] = new_g
+                heapq.heappush(todo, (new_g + heuristic(new_node), new_g, new_node))
+    
+    return (g_values, parents)
+
+def a_star(
+    from_node: T,
+    expand: typing.Callable[[T], typing.Iterable[typing.Tuple[int, T]]],
+    to_node: T,
+    heuristic: typing.Optional[typing.Callable[[T], int]] = None,
+) -> typing.Tuple[int, typing.List[T]]:
+    """
+    expand should return an iterable of (dist, successor node) tuples.
+    Returns (distance, path).
+    """
+    g_values, parents = dijkstra(from_node, to_node=to_node, expand=expand, heuristic=heuristic)
+    if to_node not in g_values:
+        raise Exception("couldn't reach to_node")
+    return (g_values[to_node], path_from_parents(parents, to_node))
+
+
+def bfs(
+    from_node: T,
+    expand: typing.Callable[[T], typing.Iterable[T]],
+    to_node: typing.Optional[T] = None
+) -> typing.Tuple[typing.Dict[T, int], typing.Dict[T, T]]:
+    """
+    expand should return an iterable of successor nodes.
+    Returns (distances, parents).
+    """
+    g_values = {from_node: 0}  # type: typing.Tuple[typing.Dict[T, int]]
+    parents = {}  # type: typing.Dict[T, T]
+    todo = [from_node]  # type: typing.List[T]
+    dist = 0
+
+    while todo:
+        new_todo = []
+        dist += 1
+        for node in todo:
+            for new_node in expand(node):
+                if new_node not in g_values:
+                    new_todo.append(new_node)
+                    parents[new_node] = node
+                    g_values[new_node] = dist
+        todo = new_todo
+        if to_node is not None and to_node in g_values:
+            break
+    
+    return (g_values, parents)
+
+def bfs_single(
+    from_node: T,
+    expand: typing.Callable[[T], typing.Iterable[T]],
+    to_node: T,
+) -> typing.Tuple[int, typing.List[T]]:
+    """
+    expand should return an iterable of successor nodes.
+    Returns (distance, path).
+    """
+    g_values, parents = bfs(from_node, to_node=to_node, expand=expand)
+    if to_node not in g_values:
+        raise Exception("couldn't reach to_node")
+    return (g_values[to_node], path_from_parents(parents, to_node))
+
+# Distances
+BLANK = object()
+def hamming_distance(a, b) -> int:
+    return sum(i is BLANK or j is BLANK or i != j for i, j in itertools.zip_longest(a, b, fillvalue=BLANK))
+def edit_distance(a, b) -> int:
+    n = len(a)
+    m = len(b)
+    dp = [[None] * (m+1) for _ in range(n+1)]
+    dp[n][m] = 0
+    def aux(i, j):
+        assert 0 <= i <= n and 0 <= j <= m
+        if dp[i][j] is not None:
+            return dp[i][j]
+        if i == n:
+            dp[i][j] = 1 + aux(i, j+1)
+        elif j == m:
+            dp[i][j] = 1 + aux(i+1, j)
+        else:
+            dp[i][j] = min((a[i] != b[j]) + aux(i+1, j+1), 1 + aux(i+1, j), 1 + aux(i, j+1))
+        return dp[i][j]
+    return aux(0, 0)
+#endregion
+
+#region Data Structures
+class Linked(typing.Generic[T], typing.Iterable[T]):
+    """
+    Represents a node in a doubly linked lists.
+
+    Can also be interpreted as a list itself.
+    Consider this to be first in the list.
+    """
+    # item: T
+    # forward: "Linked[T]"
+    # backward: "Linked[T]"
+    def __init__(self, item: T) -> None:
+        self.item = item
+        self.forward = self
+        self.backward = self
+    
+    @property
+    def val(self): return self.item
+    @property
+    def after(self): return self.forward
+    @property
+    def before(self): return self.backward
+
+    def _join(self, other: "Linked[T]") -> None:
+        self.forward = other
+        other.backward = self
+    
+    def concat(self, other: "Linked[T]") -> None:
+        """
+        Concatenates other AFTER THE END OF THE LIST,
+        i.e. before this current node.
+        """
+        first_self = self
+        last_self = self.backward
+
+        first_other = other
+        last_other = other.backward
+        # self ++ other
+        # consider last_self and first_other
+        last_self._join(first_other)
+        last_other._join(first_self)
+    
+    def concat_immediate(self, other: "Linked[T]") -> None:
+        """
+        Concatenates other IN THE "SECOND" INDEX OF THE LIST
+        i.e. after this current node.
+        """
+        self.forward.concat(other)
+    
+    def append(self, val: T) -> None:
+        """
+        Appends an item AFTER THE END OF THE LIST,
+        i.e. before this current node.
+        """
+        self.concat(Linked(val))
+    
+    def append_immediate(self, val: T) -> None:
+        """
+        Appends an item IN THE "SECOND" INDEX OF THE LIST
+        i.e. after this current node.
+        """
+        self.concat_immediate(Linked(val))
+    
+    def pop(self, n: int = 1) -> None:
+        """
+        Pops this node, as well as n others, off from the "parent list"
+        into its own list.
+        """
+        assert n > 0
+        first_self = self
+        last_self = self.move(n-1)
+
+        first_other = last_self.forward
+        last_other = first_self.backward
+        
+        last_other._join(first_other)
+        last_self._join(first_self)
+    
+    def pop_after(self, after: int, n: int = 1) -> None:
+        """
+        Pops the node n nodes after this node, as well as n others, into its
+        own list.
+        Returns the node n nodes after this node (in its new list).
+        """
+        to_return = self.move(after)
+        to_return.pop(n)  # music
+        return to_return
+
+    def delete(self) -> None:
+        """
+        Deletes this node from the "parent list" into its own list.
+        """
+        self.pop()
+    
+    def delete_other(self, n: int) -> None:
+        """
+        Deletes a node n nodes forward, or backwards if n is negative.
+        """
+        to_delete = self.move(n)
+        if to_delete is self:
+            raise Exception("can't delete self")
+        to_delete.delete()
+        del to_delete
+    
+    def move(self, n: int) -> "Linked[T]":
+        """
+        Move n nodes forward, or backwards if n is negative.
+        """
+        out = self
+        if n >= 0:
+            for _ in range(n):
+                out = out.forward
+        else:
+            for _ in range(-n):
+                out = out.backward
+        return out
+    
+    def iterate_nodes_inf(self) -> typing.Iterator["Linked[T]"]:
+        cur = self
+        while True:
+            yield cur
+            cur = cur.forward
+    
+    def iterate_nodes(self, count=1) -> typing.Iterator["Linked[T]"]:
+        for node in self.iterate_nodes_inf():
+            if node is self:
+                count -= 1
+                if count < 0:
+                    break
+            yield node
+    
+    def iterate_inf(self) -> typing.Iterator[T]:
+        return map(lambda node: node.item, self.iterate_nodes_inf())
+    
+    def iterate(self, count=1) -> typing.Iterator[T]:
+        return map(lambda node: node.item, self.iterate_nodes(count))
+    
+    def to_list(self):
+        return list(self.iterate())
+    
+    def check_correctness(self) -> None:
+        assert self.forward.backward is self
+        assert self.backward.forward is self
+    
+    def check_correctness_deep(self) -> None:
+        for node in self.iterate_nodes():
+            node.check_correctness()
+    
+    def __iter__(self) -> typing.Iterator[T]:
+        return self.iterate()
+    
+    def __repr__(self) -> str:
+        return "Linked({})".format(self.to_list())
+
+    @classmethod
+    def from_list(cls, l: typing.Iterable[T]) -> "Linked[T]":
+        it = iter(l)
+        out = cls(next(it))
+        for i in it:
+            out.concat(cls(i))
+        return out
+
+
+class UnionFind:
+    # n: int
+    # parents: List[Optional[int]]
+    # ranks: List[int]
+    # num_sets: int
+
+    def __init__(self, n: int) -> None:
+        self.n = n
+        self.parents = [None] * n
+        self.ranks = [1] * n
+        self.num_sets = n
+    
+    def find(self, i: int) -> int:
+        p = self.parents[i]
+        if p is None:
+            return i
+        p = self.find(p)
+        self.parents[i] = p
+        return p
+    
+    def in_same_set(self, i: int, j: int) -> bool:
+        return self.find(i) == self.find(j)
+    
+    def merge(self, i: int, j: int) -> None:
+        i = self.find(i)
+        j = self.find(j)
+
+        if i == j:
+            return
+        
+        i_rank = self.ranks[i]
+        j_rank = self.ranks[j]
+
+        if i_rank < j_rank:
+            self.parents[i] = j
+        elif i_rank > j_rank:
+            self.parents[j] = i
+        else:
+            self.parents[j] = i
+            self.ranks[i] += 1
+        self.num_sets -= 1
+
+
+class Grid(typing.Generic[T]):
+    """2D only!!!"""
+
+    def __init__(self, grid: typing.List[typing.List[T]]) -> None:
+        self.grid = grid
+        self.rows = len(self.grid)
+        self.cols = len(self.grid[0])
+    
+    def coords(self) -> typing.List[typing.List[int]]:
+        return [[r, c] for r in range(self.rows) for c in range(self.cols)]
+    
+    def get_row(self, row: int):
+        assert 0 <= row < self.rows, f"row {row} is OOB"
+    
+    def in_bounds(self, row: int, col: int) -> bool:
+        return 0 <= row < self.rows and 0 <= col < self.cols
+    
+    def __contains__(self, coord: typing.Union[typing.Tuple[int, int], typing.List[int]]) -> bool:
+        return self.in_bounds(*coord)
+    
+    def __getitem__(self, coord: typing.Union[typing.Tuple[int, int], typing.List[int]]) -> T:
+        return self.grid[coord[0]][coord[1]]
+#endregion
+
+#region List/Vector operations
+GRID_DELTA = [[-1, 0], [1, 0], [0, -1], [0, 1]]
+OCT_DELTA = [[1, 1], [-1, -1], [1, -1], [-1, 1]] + GRID_DELTA
+CHAR_TO_DELTA = {
+    "U": [-1, 0],
+    "R": [0, 1],
+    "D": [1, 0],
+    "L": [0, -1],
+    "N": [-1, 0],
+    "E": [0, 1],
+    "S": [1, 0],
+    "W": [0, -1],
+}
+DELTA_TO_UDLR = {
+    (-1, 0): "U",
+    (0, 1): "R",
+    (1, 0): "D",
+    (0, -1): "L",
+}
+DELTA_TO_NESW = {
+    (-1, 0): "N",
+    (0, 1): "E",
+    (1, 0): "S",
+    (0, -1): "W",
+}
+def turn_180(drowcol):
+    drow, dcol = drowcol
+    return [-drow, -dcol]
+def turn_right(drowcol):
+    # positive dcol -> positive drow
+    # positive drow -> negative dcol
+    drow, dcol = drowcol
+    return [dcol, -drow]
+def turn_left(drowcol):
+    drow, dcol = drowcol
+    return [-dcol, drow]
+def dimensions(grid: typing.List) -> typing.List[int]:
+    out = []
+    while isinstance(grid, list):
+        out.append(len(grid))
+        grid = grid[0]
+    return out
+def neighbours(coord, dimensions, deltas) -> typing.List[typing.List[int]]:
+    out = []
+    for delta in deltas:
+        new_coord = padd(coord, delta)
+        if all(0 <= c < c_max for c, c_max in zip(new_coord, dimensions)):
+            out.append(new_coord)
+    return out
+def lget(l, i):
+    if len(l) == 2: return l[i[0]][i[1]]
+    for index in i: l = l[index]
+    return l
+def lset(l, i, v):
+    if len(l) == 2:
+        l[i[0]][i[1]] = v
+        return
+    for index in i[:-1]: l = l[index]
+    l[i[-1]] = v
+def points_sub_min(points):
+    m = [min(p[i] for p in points) for i in range(len(points[0]))]
+    return [psub(p, m) for p in points]
+def points_to_grid(points, sub_min=True, flip=True):
+    if sub_min:
+        points = points_sub_min(points)
+    if not flip:
+        points = [(y, x) for x, y in points]
+    grid = make_grid(max(map(snd, points))+1, max(map(fst, points))+1, fill='.')
+    for x, y in points:
+        grid[y][x] = '#'
+    return grid
+def print_grid(grid):
+    for line in grid:
+        print(*line, sep="")
+def fst(x):
+    return x[0]
+def snd(x):
+    return x[1]
+
+def padd(x, y):
+    return [a+b for a, b in zip(x, y)]
+def pneg(v):
+    return [-i for i in v]
+def psub(x, y):
+    return [a-b for a, b in zip(x, y)]
+def pmul(m: int, v):
+    return [m * i for i in v]
+def pdot(x, y):
+    return sum(a*b for a, b in zip(x, y))
+def pdist1(x, y=None):
+    if y is not None: x = psub(x, y)
+    return sum(map(abs, x))
+def pdist2sq(x, y=None):
+    if y is not None: x = psub(x, y)
+    return sum(i*i for i in x)
+def pdist2(v):
+    return math.sqrt(pdist2sq(v))
+def pdistinf(x, y=None):
+    if y is not None: x = psub(x, y)
+    return max(map(abs, x))
+
+def signum(n: int) -> int:
+    if n > 0:
+        return 1
+    elif n == 0:
+        return 0
+    else:
+        return -1
+#endregion
+
+#region Matrices
+def matmat(a, b):
+    n, k1 = len(a), len(a[0])
+    k2, m = len(b), len(b[0])
+    assert k1 == k2
+    out = [[None] * m for _ in range(n)]
+    for i in range(n):
+        for j in range(m): out[i][j] = sum(a[i][k] * b[k][j] for k in range(k1))
+    return out
+def matvec(a, v):
+    return [j for i in matmat(a, [[x] for x in v]) for j in i]
+def matexp(a, k):
+    n = len(a)
+    out = [[int(i==j) for j in range(n)] for i in range(n)]
+    while k > 0:
+        if k % 2 == 1: out = matmat(a, out)
+        a = matmat(a, a)
+        k //= 2
+    return out
+#endregion
+
+
+#region Running
+def parse_samples(l):
+    samples = [thing.strip("\n") for thing in l]
+    while samples and not samples[-1]: samples.pop()
+    return samples
+
+def get_actual(day=None, year=None):
+    try:
+        this_file = __file__
+    except NameError:
+        this_file = "./utils.py"
+    try:
+        actual_input = open("./2021/23.input").read()
+        return actual_input
+    except FileNotFoundError:
+        pass
+    from pathlib import Path
+    cur_folder = Path(this_file).resolve().parent
+    input_path = cur_folder.joinpath("input.txt")
+    search_path = cur_folder
+    try:
+        if day is None:
+            day = int(search_path.name)
+        if year is None:
+            year = int(search_path.parent.name)
+    except Exception:
+        print("Can't get day and year.")
+        print("Backup: save 'input.txt' into the same folder as this script.")
+        return ""
+    
+    print("{} day {} input not found.".format(year, day))
+    
+    # is it time?
+    from datetime import datetime, timezone, timedelta
+    est = timezone(timedelta(hours=-5))
+    unlock_time = datetime(year, 12, day, tzinfo=est)
+    cur_time = datetime.now(tz=est)
+    delta = unlock_time - cur_time
+    if delta.days >= 0:
+        print("Remaining time until unlock: {}".format(delta))
+        return ""
+
+    while (not list(search_path.glob("*/token.txt"))) and search_path.parent != search_path:
+        search_path = search_path.parent
+    
+    token_files = list(search_path.glob("*/token.txt"))
+    if not token_files:
+        assert search_path.parent == search_path
+        print("Can't find token.txt in a parent directory.")
+        print("Backup: save 'input.txt' into the same folder as this script.")
+        return ""
+    
+    with token_files[0].open() as f:
+        token = f.read().strip()
+    
+    # importing requests takes a long time...
+    # let's do it without requests.
+    import urllib.request
+    import urllib.error
+    import shutil
+    opener = urllib.request.build_opener()
+    opener.addheaders = [("Cookie", "session={}".format(token)), ("User-Agent", "python-requests/2.19.1")]
+    print("Sending request...")
+    url = "https://adventofcode.com/{}/day/{}/input".format(year, day)
+    try:
+        with opener.open(url) as r:
+            with input_path.open(mode="wb") as f:
+                shutil.copyfileobj(r, f)
+            print("Input saved! First few lines look like:")
+            actual = input_path.open().read()
+            lines = actual.splitlines()
+            for line in lines[:16]:
+                print(line[:80] + "…" * (len(line) > 80))
+            return actual
+    except urllib.error.HTTPError as e:
+        status_code = e.getcode()
+        if status_code == 400:
+            print("Auth failed!")
+        elif status_code == 404:
+            print("Day is not out yet????")
+        else:
+            print("Request failed with code {}??".format(status_code))
+        return ""
+
+def run_samples_and_actual(samples, do_case):
+    samples = parse_samples(samples)
+    for sample in samples:
+        print("running {}:".format(repr(sample)[:100]))
+        print("-"*10)
+        do_case(sample, True)
+        print("-"*10)
+        print("#"*10)
+
+    actual_input = get_actual().strip("\n")
+
+    if actual_input:
+        print("!! running actual ({} lines): !!".format(actual_input.count("\n")+1))
+        print("-"*10)
+        do_case(actual_input, False)
+        print("-"*10)
+#endregion
+
+import sys; sys.dont_write_bytecode = True; from utils import *
+
+WAITING_ROW = 1
+WAITING_COLS = [1, 2, 4, 6, 8, 10, 11]
+ROOM_COLS = [3, 5, 7, 9]
+COST = {"A": 1, "B": 10, "C": 100, "D": 1000}
+
+def do_case(inp: str, sample=False):
+    # READ THE PROBLEM FROM TOP TO BOTTOM OK
+    def sprint(*a, **k): sample and print(*a, **k)
+    lines: typing.List[str] = inp.splitlines()
+    out = 0
+
+    FINAL_NODE = tuple()
+
+    def expand(node):
+        # (weight, node)
+        out = []
+
+        # I wrote this line of code first before doing anything else
+        # with the problem. It's good to know your search space!
+        cur_waitings, cur_rooms = node
+
+        if all(all(chr(ord('A')+i) == x for x in room) for i, room in enumerate(cur_rooms)):
+            return [(0, FINAL_NODE)]
+        
+        def is_blocked(col_1, col_2):
+            if col_1 > col_2:
+                col_1, col_2 = col_2, col_1
+            for blocked_col in range(col_1+1, col_2):
+                # This could really be improved...
+                if blocked_col in WAITING_COLS and cur_waitings[WAITING_COLS.index(blocked_col)] != "":
+                    return True
+            return False
+        
+        # Move from a room to a waiting spot.
+        for room_idx, room in enumerate(cur_rooms):
+            # The below uses the fact that:
+            # - loop variables are still in-scope after the loop is finished, and
+            # - you can add an "else" to a for loop which is run if it's not `break`ed from.
+            for room_position, to_move in enumerate(room):
+                if to_move == "":
+                    continue
+                to_move_row = 2+room_position
+                break
+            else:
+                continue
+            for waiting_idx, waiting_col in enumerate(WAITING_COLS):
+                if cur_waitings[waiting_idx] == "":
+                    if is_blocked(waiting_col, ROOM_COLS[room_idx]):
+                        continue
+
+                    new_waitings = list(cur_waitings)
+                    new_rooms = list(map(list, cur_rooms))
+
+                    # To get the cost of moving, I used the Manhattan distance
+                    # between the source and destination as it should always work
+                    # for this with a single corridor.
+                    # If the corridor was expanded, this wouldn't be as simple...
+                    cost = pdist1((to_move_row, ROOM_COLS[room_idx]), (WAITING_ROW, waiting_col)) * COST[to_move]
+                    new_waitings[waiting_idx] = to_move
+                    new_rooms[room_idx][room_position] = ""
+                    out.append((cost, (tuple(new_waitings), tuple(map(tuple, new_rooms)))))
+        
+        # Move from a waiting spot to a room.
+        for waiting_idx, waiting_col in enumerate(WAITING_COLS):
+            to_move = cur_waitings[waiting_idx]
+            if to_move == "":
+                continue
+
+            target_room_idx = ord(to_move) - ord('A')
+            target_room = cur_rooms[target_room_idx]
+
+            if target_room[0] == "" and all(x == "" or x == to_move for x in target_room[1:]):
+                for room_position in range(len(target_room))[::-1]:
+                    if target_room[room_position] != "":
+                        continue
+                    room_row = room_position + 2
+                    break
+                else:
+                    assert False
+
+                room_col = ROOM_COLS[target_room_idx]
+                if is_blocked(waiting_col, room_col):
+                    continue
+                
+                cost = pdist1((room_row, room_col), (WAITING_ROW, waiting_col)) * COST[to_move]
+
+                new_waitings = list(cur_waitings)
+                new_rooms = list(map(list, cur_rooms))
+
+                new_waitings[waiting_idx] = ""
+                new_rooms[target_room_idx][room_position] = to_move
+                out.append((cost, (tuple(new_waitings), tuple(map(tuple, new_rooms)))))
+
+        return out
+    
+
+    rooms = []
+    PART2 = ["DD", "CB", "BA", "AC"]
+    for i, room_col in enumerate(ROOM_COLS):
+        a, b = [lines[row][room_col] for row in [2, 3]]
+
+        rooms.append(tuple(a+PART2[i]+b))
+        # Replace the above with the below for part 1.
+        # This also came in handy for testing my generalised part 2 code
+        # to make sure that it works with part 1.
+        # rooms.append(tuple(a+b))
+    rooms = tuple(rooms)
+    print(rooms)
+    waitings = ("",)*len(WAITING_COLS)
+
+    # "A*" here is actually "Dijkstra, with a target node".
+    # My internal implementation also returns a path from start to finish,
+    # but I don't use it here.
+    out, _ = a_star((waitings, rooms), expand, FINAL_NODE)
+
+    if out:
+        print("out:    ", out)
+    return  # RETURNED VALUE DOESN'T DO ANYTHING, PRINT THINGS INSTEAD
+
+
+
+run_samples_and_actual([
+r"""
+#############
+#...........#
+###C#A#B#D###
+  #B#A#D#C#
+  #########
+
+""",r"""
+
+""",r"""
+
+""",r"""
+
+""",r"""
+
+""",r"""
+
+""",r"""
+
+"""], do_case)
\ No newline at end of file
diff --git a/2021/23.rs b/2021/23.rs
new file mode 100644
index 0000000..4e512c3
--- /dev/null
+++ b/2021/23.rs
@@ -0,0 +1,164 @@
+use std::collections::HashMap;
+
+enum RegOrVal {
+    Reg(usize),
+    Val(i64),
+}
+
+impl RegOrVal {
+    fn to_val(&self, reg: &[i64; 4]) -> i64 {
+        match self {
+            RegOrVal::Reg(i) => reg[*i],
+            RegOrVal::Val(v) => *v,
+        }
+    }
+}
+
+enum Instruction {
+    Inp(usize),
+    Add(usize, RegOrVal),
+    Mul(usize, RegOrVal),
+    Div(usize, RegOrVal),
+    Mod(usize, RegOrVal),
+    Eql(usize, RegOrVal),
+}
+
+impl Instruction {
+    fn exec(&self, reg: &mut [i64; 4], input: Option<i64>) {
+        match self {
+            Instruction::Inp(a) => {
+                reg[*a] = input.unwrap();
+            }
+            Instruction::Add(a, b) => {
+                reg[*a] += b.to_val(reg);
+            }
+            Instruction::Mul(a, b) => {
+                reg[*a] *= b.to_val(reg);
+            }
+            Instruction::Div(a, b) => {
+                reg[*a] /= b.to_val(reg);
+            }
+            Instruction::Mod(a, b) => {
+                reg[*a] %= b.to_val(reg);
+            }
+            Instruction::Eql(a, b) => {
+                reg[*a] = if reg[*a] == b.to_val(reg) { 1 } else { 0 };
+            }
+        }
+    }
+}
+
+fn reg_idx(reg: char) -> usize {
+    match reg {
+        'w' => 0,
+        'x' => 1,
+        'y' => 2,
+        'z' => 3,
+        _ => panic!(),
+    }
+}
+
+fn best(
+    program: &[Instruction],
+    pc: usize,
+    reg: [i64; 4],
+    visited: &mut HashMap<([i64; 4], usize), Option<i64>>,
+    smallest: bool,
+) -> Option<i64> {
+    assert!(matches!(program[pc], Instruction::Inp(_)));
+
+    if let Some(answer) = visited.get(&(reg, pc)) {
+        return *answer;
+    }
+
+    let range = if smallest {
+        [1, 2, 3, 4, 5, 6, 7, 8, 9]
+    } else {
+        [9, 8, 7, 6, 5, 4, 3, 2, 1]
+    };
+    'inputs: for input in range {
+        let mut reg = reg;
+        let mut pc = pc;
+        program[pc].exec(&mut reg, Some(input));
+        pc += 1;
+
+        while let Some(inst) = program.get(pc) {
+            if matches!(program[pc], Instruction::Inp(_)) {
+                if let Some(best) = best(program, pc, reg, visited, smallest) {
+                    visited.insert((reg, pc), Some(best * 10 + input));
+                    return Some(best * 10 + input);
+                } else {
+                    continue 'inputs;
+                }
+            } else {
+                inst.exec(&mut reg, None);
+                pc += 1;
+            }
+        }
+
+        if reg[3] == 0 {
+            visited.insert((reg, pc), Some(input));
+            return Some(input);
+        }
+    }
+
+    visited.insert((reg, pc), None);
+    None
+}
+
+pub fn solve(input: &str, smallest: bool) -> i64 {
+    let mut program = Vec::new();
+
+    for line in input.trim().split('\n') {
+        let mut parts = line.split(' ');
+        let instruction = parts.next().unwrap();
+        let reg: char = parts.next().unwrap().parse().unwrap();
+        let b_value = parts.next().map(|a| {
+            a.parse::<i64>()
+                .map(RegOrVal::Val)
+                .unwrap_or_else(|_| RegOrVal::Reg(reg_idx(a.parse::<char>().unwrap())))
+        });
+
+        let reg = reg_idx(reg);
+
+        program.push(match (instruction, reg, b_value) {
+            ("inp", reg, None) => Instruction::Inp(reg),
+            ("add", a, Some(b)) => Instruction::Add(a, b),
+            ("mul", a, Some(b)) => Instruction::Mul(a, b),
+            ("div", a, Some(b)) => Instruction::Div(a, b),
+            ("mod", a, Some(b)) => Instruction::Mod(a, b),
+            ("eql", a, Some(b)) => Instruction::Eql(a, b),
+            _ => {
+                panic!();
+            }
+        });
+    }
+
+    let mut memo = HashMap::new();
+    let answer = best(&program, 0, [0; 4], &mut memo, smallest);
+    format!("{}", answer.unwrap())
+        .chars()
+        .rev()
+        .collect::<String>()
+        .parse()
+        .unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn part_a() {
+        assert_eq!(
+            super::solve(include_str!("./2021/24.input"), false),
+            79997391969649
+        );
+    }
+
+    #[test]
+    fn part_b() {
+        assert_eq!(
+            super::solve(include_str!("./2021/24.input"), true),
+            16931171414113
+        );
+    }
+}
\ No newline at end of file
diff --git a/2021/23.test b/2021/23.test
new file mode 100644
index 0000000..be5da55
--- /dev/null
+++ b/2021/23.test
@@ -0,0 +1,23 @@
+#############
+#...........#
+###C#A#B#D###  
+  #D#C#B#A#
+  #D#B#A#C#
+  #B#A#D#C#
+  #########
+
+############# 5
+#A..........#
+###C#.#B#D###  
+  #D#C#B#A#
+  #D#B#A#C#
+  #B#A#D#C#
+  #########
+
+############# 50
+#AC.B.......#
+###C#.#B#D###  
+  #D#.#B#A#
+  #D#.#A#C#
+  #B#A#D#C#
+  #########
diff --git a/2021/24.input b/2021/24.input
new file mode 100644
index 0000000..1999106
--- /dev/null
+++ b/2021/24.input
@@ -0,0 +1,252 @@
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 12
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 4
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 11
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 11
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 13
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 5
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 11
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 11
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 14
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 14
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -10
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 7
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 11
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 11
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -9
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 4
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -3
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 6
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 13
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 5
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -5
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 9
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -10
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -4
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 14
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -5
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 14
+mul y x
+add z y
\ No newline at end of file
diff --git a/2021/24.py b/2021/24.py
new file mode 100644
index 0000000..238a3c2
--- /dev/null
+++ b/2021/24.py
@@ -0,0 +1,99 @@
+import functools
+import sys
+inf = './2021/24.input'
+
+ll = [x for x in open(inf).read().strip().split('\n')]
+
+
+
+# BEGIN <UNUSED SECTION>
+vs = 'wxyz'
+def simulate(line, state):
+	state = list(state)
+	cmd = line.split(" ")[0]
+	if cmd == 'inp':
+		raise Exception("")
+	a = line.split(" ")[1]
+	b = line.split(" ")[2]
+	def parse(x):
+		if x in vs:
+			return state[vs.index(x)]
+		return int(x)
+	if cmd == 'add':
+		state[vs.index(a)] += parse(b)
+	if cmd == 'mul':
+		state[vs.index(a)] *= parse(b)
+	if cmd == 'div':
+		state[vs.index(a)] //= parse(b)
+	if cmd == 'mod':
+		state[vs.index(a)] %= parse(b)
+	if cmd == 'eql':
+		state[vs.index(a)] = int(state[vs.index(a)] == parse(b))
+	return tuple(state)
+@functools.lru_cache(maxsize=None)
+def run2(ch, zstart, w):
+	state = (w, 0, 0, zstart)
+	for i in range(ch*18+1, ch*18+18):
+		state = simulate(ll[i], state)
+	r = state[3]
+	print(run(ch, zstart, w) == r)
+	return r
+# END </UNUSED SECTION>
+
+
+# my input
+#AX = [13, 11, 15, -11, 14, 0, 12, 12, 14, -6, -10, -12, -3, -5]
+#DZ = [1, 1, 1, 26, 1, 26, 1, 1, 1, 26, 26, 26, 26, 26]
+#AY = [13, 10, 5, 14, 5, 15, 4, 11, 1, 15, 12, 8, 14, 9]
+
+AX = []
+DZ = []
+AY = []
+for lineno, line in enumerate(ll):
+	if "add x " in line and "add x z" not in line:
+		AX.append(int(line.split()[2]))
+	if "div z " in line:
+		DZ.append(int(line.split()[2]))
+	if "add y " in line and lineno%18 == 15:
+		AY.append(int(line.split()[2]))
+print("Extracted from input", AX, DZ, AY)
+
+if len(AX) != 14 or len(DZ) != 14 or len(AY) != 14:
+	raise Exception("couldn't understand your input")
+
+def run(ch, z, w):
+	x = AX[ch] + (z % 26)
+	z = z // DZ[ch]
+	if x != w:
+		z *= 26
+		z += w + AY[ch]
+	return z
+
+Zbudget = [26**len([x for x in range(len(DZ)) if DZ[x]==26 and x >= i]) for i in range(len(DZ))]
+print("Threshold for giving up due to Z being too high, at each stage has been calculated as", Zbudget)
+CANDIDATES = list(range(1, 10))
+@functools.lru_cache(maxsize=None)
+def search(ch, zsofar):
+	if ch == 14:
+		if zsofar == 0:
+			return [""]
+		return []
+	if zsofar > Zbudget[ch]:
+		return []
+	xwillbe = AX[ch] + zsofar % 26
+	wopts = CANDIDATES
+	if xwillbe in range(1, 10):
+		wopts = [xwillbe]
+	ret = []
+	for w in wopts:
+		znext = run(ch, zsofar, w)
+		nxt = search(ch + 1, znext)
+		for x in nxt:
+			ret.append(str(w) + x)
+	return ret
+
+solns = search(0, 0)
+solns = [int(x) for x in solns]
+print("num solutions", len(solns))
+print(max(solns), min(solns))
+
diff --git a/2021/24.test b/2021/24.test
new file mode 100644
index 0000000..e69de29
diff --git a/2021/25.input b/2021/25.input
new file mode 100644
index 0000000..21bf92c
--- /dev/null
+++ b/2021/25.input
@@ -0,0 +1,137 @@
+vv.vv...v>>>.v.>vv.>v>..>.....>.v>.>......v.>vvv.v.>.v.v>>>..v...>.v>.vv>..v>.>.>...>.v.v.>>>v>.>>>>........>..v>v.>v>>.....>.vv.>v..>....v
+.>>v>vv.>v..>>vv.....>....v>>.vv>.>.v.>>v.v>.vvvvv.>.>>>>v.v...>.vv.vvvvv.>vv..>.v>..>..>>...vv....>>.v.>v>>v..v.>....vv....>.v.....>.v>>..
+>..vvv...v>v>....v.>>v.......>v.....v.v....v.....vv.>>>.vv..>..>v....v...>.vv..>.v>>..>...v..v.....>..v>>....>v>v..v...v>......>..vv...>..>
+.>.>.>..v>...>>vvv..v..>...>.v.v.vv>>vv..v.v..>..>vv>v....vv.v.v..>v.>..v.>>..v...v..v>v....vvv.>>.>.v.>vv>v.>vvv.>v>>...v>v..>.>.>...v.>>>
+..>v.v..vv>.>v>..v.>>>>vvv..>.vv.v.v>>..>>>v>.>>>v.>>..vv.v...>>..v..v>v..>>vv..>v>>>v.v...>>.>.v.>.vv.>vv.>>.v>v.>v...v.v.>vv..>>....v>..v
+v.>vv.>>..v>v..>v.v..>.>..vv.v.>...>>.>v..v..>>v.>v..vv>v.>v.>..vv....v>v..>>>....v>...>>..v.>.v>.v.v.>>..>..>...vv>..vv...v.>v.>.>.v..v.vv
+>v..v.>v>>>..>v...>>..>....v.>....v.vv>..>v>.>>.>.....>>.vv>...>vv.v.>>v..v...>...vv...v>..v>>.>>.>..v.>....>.vv.v>.>.>..v..>v>v>>v.>>...>v
+.vv.>v>>....>>..>v..v.v>...>v>.v..v.>.>>....>...>..vv.>>v>>v...v>.>.>.v.v...>...v>.v>>.>...>.v>...v....>..>v.>.v.>>..>vv>.v>..v.v.v..>>.>>.
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\ No newline at end of file
diff --git a/2021/25.py b/2021/25.py
new file mode 100644
index 0000000..e46b425
--- /dev/null
+++ b/2021/25.py
@@ -0,0 +1,49 @@
+#!/usr/bin/python3
+import sys
+import heapq
+import itertools
+import re
+import ast
+from collections import defaultdict, Counter, deque
+from copy import deepcopy
+
+#submit(len(G), part="a", day=25, year=2021)
+infile = sys.argv[1] if len(sys.argv)>1 else './2021/25.input'
+data = open(infile).read().strip()
+
+G = []
+for line in data.split('\n'):
+  assert line.strip() == line
+  G.append(line)
+R = len(G)
+C = len(G[0])
+
+t = 0
+while True:
+  t += 1
+  moved = False
+  G2 = [[G[r][c] for c in range(C)] for r in range(R)]
+  for r in range(R):
+    for c in range(C):
+      if G[r][c] == '>':
+        if G[r][(c+1)%C] == '.':
+          moved = True
+          G2[r][(c+1)%C] = '>'
+          G2[r][c] = '.'
+  G3 = [[G2[r][c] for c in range(C)] for r in range(R)]
+  for r in range(R):
+    for c in range(C):
+      if G2[r][c] == 'v' and G2[(r+1)%R][c] == '.':
+        moved = True
+        G3[(r+1)%R][c] = 'v'
+        G3[r][c] = '.'
+  if not moved:
+    print(t)
+    sys.exit(0)
+  G = G3
+  #print(t, moved)
+  #for r in range(R):
+  #  row = ''
+  #  for c in range(C):
+  #    row += G[r][c]
+  #  print(row)
diff --git a/2021/25.test b/2021/25.test
new file mode 100644
index 0000000..73a37cc
--- /dev/null
+++ b/2021/25.test
@@ -0,0 +1,9 @@
+v...>>.vv>
+.vv>>.vv..
+>>.>v>...v
+>>v>>.>.v.
+v>v.vv.v..
+>.>>..v...
+.vv..>.>v.
+v.v..>>v.v
+....v..v.>
\ No newline at end of file