105 lines
2.6 KiB
Python
105 lines
2.6 KiB
Python
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#!/bin/python3
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import sys
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sys.setrecursionlimit(1500)
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hmap = list()
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with open('day12.txt', 'r') as f:
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for line in f:
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hmap.append(line.strip())
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h = len(hmap)
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w = len(hmap[0])
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for y in range(h):
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for x in range(w):
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if hmap[y][x] == 'S':
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start = (x, y)
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if hmap[y][x] == 'E':
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end = (x, y)
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def get_elevation(char):
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if char == 'S':
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return ord('a')
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if char == 'E':
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return ord('z')
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return ord(char)
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def get_adjacents(pos):
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(x, y) = pos
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return [(x-1, y), (x+1, y), (x, y-1), (x, y+1)]
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def in_bounds(pos):
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(x, y) = pos
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return x >= 0 and x < w and y >= 0 and y < h
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def get_char(hmap, pos):
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(x, y) = pos
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return hmap[y][x]
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def valid_jump(hmap, pos, adj):
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poschar = get_char(hmap, pos)
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adjchar = get_char(hmap, adj)
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poselev = get_elevation(poschar)
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adjelev = get_elevation(adjchar)
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return poselev + 1 >= adjelev
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best_cost = {}
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def find_path(hmap, path, pos):
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if get_char(hmap, pos) == 'E':
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return [path]
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paths = list()
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for adj in get_adjacents(pos):
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if adj not in path and in_bounds(adj) and valid_jump(hmap, pos, adj):
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if adj not in best_cost or best_cost[adj] > len(path):
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best_cost[adj] = len(path)
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new_path = set.copy(path)
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new_path.add(adj)
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paths.extend(find_path(hmap, new_path, adj))
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return paths
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shortest = None
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paths = find_path(hmap, set([start]), start)
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for path in paths:
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if not shortest or len(path) < shortest:
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shortest = len(path)
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print('part1', shortest - 1)
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trail_lengths = {}
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def valid_jump2(hmap, pos, adj):
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poschar = get_char(hmap, pos)
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adjchar = get_char(hmap, adj)
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poselev = get_elevation(poschar)
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adjelev = get_elevation(adjchar)
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return adjelev + 1 >= poselev
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def find_trail(hmap, trail, pos):
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for adj in get_adjacents(pos):
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if adj not in trail and in_bounds(adj) and valid_jump2(hmap, pos, adj):
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trail_length = len(trail) + 1
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if adj not in trail_lengths or trail_lengths[adj] > trail_length:
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trail_lengths[adj] = trail_length
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new_trail = list.copy(trail)
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new_trail.append(adj)
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find_trail(hmap, new_trail, adj)
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find_trail(hmap, [end], end)
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shortest = None
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for y in range(h):
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for x in range(w):
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if (x, y) in trail_lengths:
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if get_elevation(get_char(hmap, (x, y))) == ord('a'):
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trail_length = trail_lengths[(x, y)]
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if not shortest or trail_length < shortest:
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shortest = trail_length
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print('part2', shortest - 1)
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