Anders Englöf Ytterström
92df810943
BFS, baby. 2 things got me. * S position was not (0,0) in the puzzle input. Such embarrasment to loose time over something so stupid. * I asumed the elevation was fixed to to increase AND DECREASE by 1. From the problem description: > To avoid needing to get out your climbing gear, the elevation of the > destination square can be at most one higher than the elevation of > your current square; that is, if your current elevation is m, you > could step to elevation n, but not to elevation o. _(This also means > that the elevation of the destination square can be much lower than > the elevation of your current square.)_ This means elevation only can _increase_ by one, but _decrease_ with more. So my wrong code: 0 <= abs(n - e) <= 1 got fixed with: n - e <= 1 For pt 2, I reused the loop to find S to collect all "a" positions, and looped them as starting points. Execution time is not the best, but it works.
58 lines
1.5 KiB
Python
58 lines
1.5 KiB
Python
import re
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from collections import deque, Counter, defaultdict
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from heapq import heappop, heappush
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from itertools import compress, combinations, chain, permutations
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from output import matrix, D, DDa, vvdbg, DD, ADJ, ints, mhd, mdbg, vdbg, cw, ccw, bk
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def solve(data):
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M, H, W = matrix(data)
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E = S = None
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p1 = p2 = H * W
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SP = []
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for rr in range(H):
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for cc in range(W):
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if M[rr][cc] == "E":
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E = (rr, cc)
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if M[rr][cc] == "S":
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S = (rr, cc)
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SP.append((rr, cc))
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if M[rr][cc] == "a":
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SP.append((rr, cc))
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M = [list(row) for row in M]
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for rc, v in [(S, "a"), (E, "z")]:
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r, c = rc
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M[r][c] = v
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for sp in SP:
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Q = [(sp, ord("a"), 0)]
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seen = set()
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while Q:
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yx, e, s = Q.pop(0)
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if yx in seen:
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continue
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seen.add(yx)
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if yx == E:
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if sp == S:
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p1 = s
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p2 = min(p2, s)
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y, x = yx
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for dy, dx in D:
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if 0 <= y + dy < H and 0 <= x + dx < W:
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n = ord(M[y + dy][x + dx])
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if n - e <= 1:
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Q.append(((y + dy, x + dx), n, s + 1))
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return p1, p2
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if __name__ == "__main__":
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with open("./input/12.txt", "r") as f:
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inp = f.read().strip()
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p1, p2 = solve(inp)
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print(p1)
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print(p2)
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assert p1 == 517
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assert p2 == 512
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