Solve 2021 day 20, 21, 23, 25

2021/d20.py

@@ -0,0 +1,51 @@
+from lib import get_data
+
+data = get_data(__file__)
+
+for rounds in [2, 50]:
+    algo, img = data.strip().split("\n\n")
+    algo = algo.replace("\n", "")
+
+    xs = set()
+    img = img.splitlines()
+    for row in range(len(img)):
+        for col in range(len(img[0])):
+            if img[row][col] == "#":
+                xs.add((row, col))
+
+    for i in range(rounds):
+        y_min = min(v[0] for v in xs) - 6
+        y_max = max(v[0] for v in xs) + 6
+        x_min = min(v[1] for v in xs) - 6
+        x_max = max(v[1] for v in xs) + 6
+
+        nxs = set()
+        for row in range(y_min, y_max + 1):
+            for col in range(x_min, x_max + 1):
+                bin = ""
+                for ro in range(3):
+                    for co in range(3):
+                        if (row + ro, col + co) in xs:
+                            bin += "1"
+                        else:
+                            bin += "0"
+                bin = int(bin, 2)
+                if algo[bin] == "#":
+                    nxs.add((row, col))
+
+        xs = nxs
+        y_min_trim = y_min + 7
+        y_max_trim = y_max - 8
+        x_min_trim = x_min + 7
+        x_max_trim = x_max - 8
+
+        # special clean-up required because input creates pixels when there
+        # are no other pixels around (0b0_0000_0000)
+        if i % 2 == 1:
+            xs = [
+                (r, c)
+                for (r, c) in xs
+                if y_min_trim <= r <= y_max_trim and x_min_trim <= c <= x_max_trim
+            ]
+
+    print(len(xs))

2021/d21.py

@@ -0,0 +1,65 @@
+from lib import get_data
+from lib import ints
+from collections import defaultdict
+
+
+FIELD = 10
+DICE = 100
+dice = -1
+
+data = get_data(__file__)
+
+_, p1, _, p2 = ints(data)
+pos = [p1 - 1, p2 - 1]
+scores = [0, 0]
+
+dice_rolls = 0
+not_done = True
+while not_done:
+    for p in range(len(scores)):
+        dice_rolls += 3
+        for _ in range(3):
+            dice += 1 % DICE
+            pos[p] = (pos[p] + (dice + 1)) % FIELD
+        scores[p] += pos[p] + 1
+        if scores[p] >= 1000:
+            not_done = False
+            break
+
+r = min(scores) * dice_rolls
+print(r)
+
+_, p1, _, p2 = ints(data)
+pos = (p1 - 1, p2 - 1)
+scores = (0, 0)
+unis = defaultdict(int)
+won = [0, 0]
+unis[(0, pos, scores)] += 1
+
+while unis:
+    nunis = defaultdict(int)
+    for (turn, opos, scores), count in unis.items():
+        other = (turn + 1) % 2
+        poss = [opos[turn]]
+        for _ in range(3):
+            nposs = []
+            for dice in range(1, 3 + 1):
+                for pos in poss:
+                    npos = (pos + dice) % FIELD
+                    nposs.append(npos)
+            poss = nposs
+
+        for npos_player in poss:
+            score = scores[turn] + npos_player + 1
+            if score >= 21:
+                won[turn] += count
+            else:
+                nscores = list(scores)
+                nscores[turn] = score
+                npos = list(opos)
+                npos[turn] = npos_player
+                state = (other, tuple(npos), tuple(nscores))
+                nunis[state] += count
+    unis = nunis
+
+print(max(won))

2021/d22.py

@@ -0,0 +1,27 @@
+from lib import get_data
+from lib import ints
+
+data = get_data(__file__)
+
+limit = 50
+ps = set()
+for i, line in enumerate(data.splitlines()):
+    x_min, x_max, y_min, y_max, z_min, z_max = ints(line)
+    for x in range(max(x_min, -limit), min(x_max, limit) + 1):
+        for y in range(max(y_min, -limit), min(y_max, limit) + 1):
+            for z in range(max(z_min, -limit), min(z_max, limit) + 1):
+                if line.startswith("on"):
+                    ps.add((x, y, z))
+                elif line.startswith("off"):
+                    if (x, y, z) in ps:
+                        ps.remove((x, y, z))
+                else:
+                    assert False
+print(len(ps))
+
+
+# For part 1, we were limited to an area of -50..50 for all three directions.
+# For part 2, this limitation is no longer in place. That means we cannot keep
+# track of all the points individually. Instead, it will be necessary. To keep
+# track of regions. Ultimately, we then have to perform arithmetic on the
+# regions. This is not trivial enough for me right now.

2021/d23.py

@@ -0,0 +1,143 @@
+import heapq
+from lib import get_data
+from lib import Grid2D
+from collections import deque
+from collections import defaultdict
+
+CHAR_COSTS = {"A": 1, "B": 10, "C": 100, "D": 1000}
+HALL_SPOTS = set([(1, x) for x in [1, 2, 4, 6, 8, 10, 11]])
+
+for n_amphs in [2, 4]:
+    AMPH_SPOTS = {}
+    for i, c in enumerate("ABCD"):
+        spots = [(r, 3 + i * 2) for r in range(2, 2 + n_amphs)]
+        AMPH_SPOTS[c] = tuple(spots)
+
+    data = get_data(__file__)
+    lines = data.splitlines()
+    if n_amphs == 4:
+        lines.insert(-2, "  #D#C#B#A#  ")
+        lines.insert(-2, "  #D#B#A#C#  ")
+    lines[-2] = lines[-2] + "  "
+    lines[-1] = lines[-1] + "  "
+    data = "\n".join(lines)
+
+    g = Grid2D(data)
+    GRID_EMPTY = g.clone()
+
+    def mdist(p1, p2):
+        return abs(p1[0] - p2[0]) + abs(p1[1] - p2[1])
+
+    poss = []
+    for c in "ABCD":
+        for coord in g.find(c):
+            poss.append((coord[0], coord[1], c, False))
+            GRID_EMPTY[coord] = "."
+    poss = tuple(poss)
+
+    def dist(n1, n2):
+        """cost from node to node"""
+        if n1 == 0:
+            return 0
+        return n2[1] - n1[1]
+
+    def h(node):
+        """heuristic function (never overestimate)"""
+        cost = 0
+        for r, c, char, _ in node[0]:
+            if (r, c) not in AMPH_SPOTS[char]:
+                cost += mdist((r, c), AMPH_SPOTS[char][0]) * CHAR_COSTS[char]
+        return cost
+
+    def is_goal(node):
+        for r, c, char, _ in node[0]:
+            if (r, c) in AMPH_SPOTS[char]:
+                continue
+            return False
+        return True
+
+    def find_accessible_spots(pos: tuple[int, int], char, blocked):
+        start = (pos, 0)
+        visited = set()
+        queue = deque([start])
+        cost = CHAR_COSTS[char]
+
+        options = []
+        while queue:
+            pos, dist = queue.popleft()
+            if pos in visited:
+                continue
+            visited.add(pos)
+
+            for neighbor in GRID_EMPTY.neighbors_ort(pos):
+                if neighbor in blocked:
+                    continue
+                if GRID_EMPTY[neighbor] != ".":
+                    continue
+                if neighbor not in visited:
+                    new_state = (neighbor, dist + cost)
+                    queue.append(new_state)
+                    options.append(new_state)
+        return options
+
+    def neighbors(node):
+        nbs = []
+
+        blocked = []
+        blocked_to_char = defaultdict(str)
+        for r, c, char, _ in node[0]:
+            blocked.append((r, c))
+            blocked_to_char[(r, c)] = char
+
+        for i, (r, c, char, moved) in enumerate(node[0]):
+            if moved and (r, c) in AMPH_SPOTS[char]:
+                continue
+
+            for pos, dist in find_accessible_spots((r, c), char, blocked):
+                # cannot move to hall spots twice
+                if pos in HALL_SPOTS and moved:
+                    continue
+
+                # can only move to hall spot or amph spot (of the right type)
+                if not (pos in HALL_SPOTS or pos in AMPH_SPOTS[char]):
+                    continue
+
+                # only move into amph spot if all lower spots are already occupied by the correct amph
+                if pos in AMPH_SPOTS[char] and not all(
+                    blocked_to_char[AMPH_SPOTS[char][i]] == char
+                    for i in range(
+                        AMPH_SPOTS[char].index(pos) + 1, len(AMPH_SPOTS[char])
+                    )
+                ):
+                    continue
+
+                amphs = list(node[0])
+                amphs[i] = (pos[0], pos[1], char, True)
+                neighbor = (tuple(amphs), node[1] + dist)
+                nbs.append(neighbor)
+        return nbs
+
+    starts = [(poss, 0)]
+    open_set = []
+    g_score = {}
+    cost = None
+
+    for start in starts:
+        heapq.heappush(open_set, (h(start), start))
+        g_score[start] = dist(0, start)
+
+    while open_set:
+        current_f_score, current = heapq.heappop(open_set)
+        if is_goal(current):
+            assert current_f_score == g_score[current]
+            cost = g_score[current]
+            break
+
+        for neighbor in neighbors(current):
+            tentative_g_score = g_score[current] + dist(current, neighbor)
+            if neighbor not in g_score or tentative_g_score < g_score[neighbor]:
+                g_score[neighbor] = tentative_g_score
+                f_score = g_score[neighbor] + h(neighbor)
+                heapq.heappush(open_set, (f_score, neighbor))
+
+    print(cost)

2021/d24.py

@@ -0,0 +1,63 @@
+from lib import get_data
+
+data = get_data(__file__)
+
+# lines = data.splitlines()
+# blocks = [lines[i:i + 18] for i in range(0, len(lines), 18)]
+# blocks = zip(*blocks)
+# for row in blocks:
+#     print("; ".join(set(row)))
+
+def run(number=None):
+    inputs = []
+    if number is not None:
+        for c in str(number):
+            if c == "0":
+                return
+            inputs.append(int(c))
+        inputs = list(reversed(inputs))
+    else:
+        inputs = None
+
+    regs = {c: 0 for c in "wxyz"}
+    for i, line in enumerate(data.splitlines()):
+        if line.startswith("inp"):
+            if inputs is not None:
+                if inputs == []:
+                    print(number, regs)
+                    return
+                else:
+                    op, a = line.split()
+                    regs[a] = inputs.pop()
+            else:
+                # print(regs)
+                op, a = line.split()
+                regs[a] = int(input(f"{i // 14} > "))
+            continue
+
+        op, a, b = line.split()
+        b = regs[b] if b in regs else int(b)
+        match op:
+            case "add":
+                regs[a] = regs[a] + b
+            case "mul":
+                regs[a] = regs[a] * b
+            case "div":
+                regs[a] = regs[a] // b
+            case "mod":
+                regs[a] = regs[a] % b
+            case "eql":
+                regs[a] = 1 if regs[a] == b else 0
+
+
+    print("end", inputs, number, regs)
+
+
+run(19111111111111)
+
+# while True:
+#     try:
+#         run()
+#     except KeyboardInterrupt:
+#         print("\n restart <")
+#         pass

2021/d25.py

@@ -0,0 +1,29 @@
+from lib import get_data
+from lib import Grid2D
+
+data = get_data(__file__)
+
+g = Grid2D(data)
+seen = set()
+for i in range(10**9):
+    if g.hash() in seen:
+        print(i)
+        break
+
+    seen.add(g.hash())
+    blocked = set(g.find(">v"))
+    for p in g.find(">"):
+        np = (p[0], (p[1] + 1) % g.n_cols)
+        if np in blocked:
+            continue
+        g[p] = "."
+        g[np] = ">"
+
+    blocked = set(g.find(">v"))
+    for p in g.find("v"):
+        np = ((p[0] + 1) % g.n_rows , p[1])
+        if np in blocked:
+            continue
+        g[p] = "."
+        g[np] = "v"
+

README.md

@@ -191,7 +191,12 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 17:  21:59   (Not tricky again but struggling for no reason.)
 - Day 18: 162:00   (I couldn't figure out how to solve it as a tree so I did the basic way.)
 - Day 19:
-- Day 20:
+- Day 20: 105:00   (That wasn't easy but was able to solve in one go.)
+- Day 21:  37:45   (Wasn't hard but I was just too slow.)
+- Day 22:
+- Day 23:  81:38   (Fun but obviously not competitive.)
+- Day 24:
+- Day 25:  15:43   (That could have been much much faster.)
 
 ## AoC 2022
 

lib.py

@@ -59,6 +59,10 @@ class Grid2D:
     def hash(self):
         return tuple(map(lambda row: tuple(row), self.grid))
 
+    def clone(self):
+        from copy import deepcopy
+        return deepcopy(self)
+
     def clone_with_val(self, val):
         c = Grid2D("d\nd")
         c.n_rows = self.n_rows