Solve 2016:24 p1-2 "Air Duct Spelunking"

BFS baby.

2016-python2/output/day_24.py

@@ -0,0 +1,77 @@
+import re
+from collections import Counter, defaultdict, deque
+from heapq import heappop, heappush
+from itertools import chain, combinations, compress, permutations
+
+from output import ADJ, DD, D, ints, matrix, mdbg, mhd, vdbg
+
+
+def solve(data):
+    grid, H, W = matrix(data)
+    dests = {
+        v: (y, x) for y, r in enumerate(grid) for x, v in enumerate(r) if v.isdigit()
+    }
+    S0 = dests["0"]
+    del dests["0"]
+    p1 = travel(dests, grid, H, W, S0)
+    p2 = travel(dests, grid, H, W, S0, goback=True)
+    return p1, p2
+
+
+def travel(dests, grid, H, W, S0, goback=False):
+    shortest = float("inf")
+    for goals in permutations(dests.items()):
+        goals = list(goals)
+        if goback:
+            goals += [("0", S0)]
+        t = 0
+        S = S0
+        for _, E in goals:
+            seen = set()
+            q = [(S, 0)]
+            while q:
+                pos, w = q.pop(0)
+                if pos == E:
+                    t += w
+                    break
+                if pos in seen:
+                    continue
+                seen.add(pos)
+                y, x = pos
+                for dy, dx in D:
+                    if not (0 <= dy + y < H and 0 <= dx + x < W):
+                        continue
+                    if grid[dy + y][dx + x] != "#":
+                        q.append(((dy + y, dx + x), w + 1))
+            S = E
+        shortest = min(shortest, t)
+    return shortest
+
+
+if __name__ == "__main__":
+    # use dummy data
+    inp = """
+    ###########
+    #0.1.....2#
+    #.#######.#
+    #4.......3#
+    ###########
+    """.strip()
+
+    # uncomment to instead use stdin
+    # import sys; inp = sys.stdin.read().strip()
+
+    # uncomment to use AoC provided puzzle input
+    with open("./input/24.txt", "r") as f:
+        inp = f.read().strip()
+
+    # uncomment to do initial data processing shared by part 1-2
+    p1, p2 = solve(inp)
+
+    print(p1)
+    print(p2)
+
+    # uncomment and replace 0 with actual output to refactor code
+    # and ensure nonbreaking changes
+    # assert p1 == 0
+    # assert p2 == 0