My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2022/12
+40
+40
2022/day12.py
+40
2022/day12.py
···
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import fileinput
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from collections import deque
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from utils import Point
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# Parse input.
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board = {}
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for y, line in enumerate(fileinput.input()):
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for x, c in enumerate(line.strip()):
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board[Point(x, y)] = c
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if c == 'S':
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start = Point(x, y)
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board[start] = 'a'
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elif c == 'E':
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end = Point(x, y)
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board[end] = 'z'
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def bfs(start):
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horizon = deque([(start, 0)])
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seen = set()
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while horizon:
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p, depth = horizon.popleft()
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if p in seen:
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continue
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elif p == end:
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return depth
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seen.add(p)
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for n in p.neighbours(): # returns the 4 adjacent points
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if n not in board:
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continue
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if (ord(board[n]) - 1 <= ord(board[p])):
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horizon.append((n, depth + 1))
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return 1e9
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print("Part 1:", bfs(start))
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print("Part 2:", min(bfs(s) for s in board if board[s] == 'a'))