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| 1 | +#!/usr/bin/env python3 |
| 2 | +from collections import defaultdict |
| 3 | +from heapq import heappop, heappush |
| 4 | +from itertools import product |
| 5 | +from sys import maxsize |
| 6 | + |
| 7 | +import matplotlib.pyplot as plt |
| 8 | +import networkx as nx |
| 9 | + |
| 10 | +import adventofcode |
| 11 | + |
| 12 | +t1 = [ |
| 13 | + '#.#####################', |
| 14 | + '#.......#########...###', |
| 15 | + '#######.#########.#.###', |
| 16 | + '###.....#.>.>.###.#.###', |
| 17 | + '###v#####.#v#.###.#.###', |
| 18 | + '###.>...#.#.#.....#...#', |
| 19 | + '###v###.#.#.#########.#', |
| 20 | + '###...#.#.#.......#...#', |
| 21 | + '#####.#.#.#######.#.###', |
| 22 | + '#.....#.#.#.......#...#', |
| 23 | + '#.#####.#.#.#########v#', |
| 24 | + '#.#...#...#...###...>.#', |
| 25 | + '#.#.#v#######v###.###v#', |
| 26 | + '#...#.>.#...>.>.#.###.#', |
| 27 | + '#####v#.#.###v#.#.###.#', |
| 28 | + '#.....#...#...#.#.#...#', |
| 29 | + '#.#########.###.#.#.###', |
| 30 | + '#...###...#...#...#.###', |
| 31 | + '###.###.#.###v#####v###', |
| 32 | + '#...#...#.#.>.>.#.>.###', |
| 33 | + '#.###.###.#.###.#.#v###', |
| 34 | + '#.....###...###...#...#', |
| 35 | + '#####################.#', |
| 36 | +] |
| 37 | + |
| 38 | +def parse(lines): |
| 39 | + grid = defaultdict(lambda: '#') |
| 40 | + for y, row in enumerate(lines): |
| 41 | + for x, c in enumerate(row): |
| 42 | + grid[(x, y)] = c |
| 43 | + return grid |
| 44 | + |
| 45 | +def adjacent(pos): |
| 46 | + # clockwise, starting up, negative y is up |
| 47 | + for d in [(0, -1), (1, 0), (0, 1), (-1, 0)]: |
| 48 | + yield pos[0] + d[0], pos[1] + d[1] |
| 49 | + |
| 50 | +def walkable(grid, icy, pos): |
| 51 | + c = grid[pos] |
| 52 | + dirs = {'^': (0, -1), '>': (1, 0), 'v': (0, 1), '<': (-1, 0)} |
| 53 | + if icy and c in dirs: |
| 54 | + d = dirs[c] |
| 55 | + adj = [(pos[0] + d[0], pos[1] + d[1])] |
| 56 | + else: |
| 57 | + adj = adjacent(pos) |
| 58 | + return adj |
| 59 | + |
| 60 | +def find_route(lines, icy): |
| 61 | + grid = parse(lines) |
| 62 | + start = (1, 0) |
| 63 | + destination = (len(lines[0]) - 2, len(lines) - 1) |
| 64 | + |
| 65 | + distances = {} |
| 66 | + q = [(maxsize, 0, start, {start})] |
| 67 | + while q: |
| 68 | + _, dist, pos, been = heappop(q) |
| 69 | + if pos not in distances or distances[pos] <= dist: |
| 70 | + distances[pos] = dist |
| 71 | + adj = walkable(grid, icy, pos) |
| 72 | + adj = [np for np in adj if grid[np] != '#' and np not in been] |
| 73 | + for np in adj: |
| 74 | + heappush(q, (maxsize - (dist + 1), dist + 1, np, been | {np})) |
| 75 | + |
| 76 | + return distances[destination] |
| 77 | + |
| 78 | +def part1(lines): |
| 79 | + """ |
| 80 | + # >>> part1(t1) |
| 81 | + 94 |
| 82 | + """ |
| 83 | + return find_route(lines, True) |
| 84 | + |
| 85 | +def display(grid, been, w, h): |
| 86 | + for y in range(h): |
| 87 | + for x in range(w): |
| 88 | + ic = '+' if (x, y) in been else grid[(x, y)] |
| 89 | + if ic == '#': |
| 90 | + ic = ' ' |
| 91 | + print(ic, end='') |
| 92 | + print() |
| 93 | + |
| 94 | +def part2(lines): |
| 95 | + """ |
| 96 | + # >>> part2(t1) |
| 97 | + 154 |
| 98 | + """ |
| 99 | + return route_using_networkx(lines) |
| 100 | + |
| 101 | +def find_graph(lines): |
| 102 | + grid = parse(lines) |
| 103 | + w, h = len(lines[0]), len(lines) |
| 104 | + start = (1, 0) |
| 105 | + destination = (len(lines[0]) - 2, len(lines) - 1) |
| 106 | + nodes = find_nodes(grid, w, h, start, destination) |
| 107 | + weights = find_weights(grid, nodes) |
| 108 | + return weights, start, destination |
| 109 | + |
| 110 | +def find_weights(grid, nodes): |
| 111 | + weights = {} |
| 112 | + for node in nodes: |
| 113 | + clear = set(p for p in adjacent(node) if grid[p] != '#') |
| 114 | + for np in clear: |
| 115 | + been = {node, np} |
| 116 | + while np not in nodes: |
| 117 | + adj = walkable(grid, False, np) |
| 118 | + npl = [p for p in adj if grid[p] != '#' and p not in been] |
| 119 | + if not npl: |
| 120 | + break |
| 121 | + assert len(npl) == 1 |
| 122 | + been.add(npl[0]) |
| 123 | + np = npl[0] |
| 124 | + if np in nodes: |
| 125 | + edge = (min(node, np), max(node, np)) |
| 126 | + weight = len(been) - 1 |
| 127 | + weights[edge] = weight |
| 128 | + return weights |
| 129 | + |
| 130 | +def find_nodes(grid, w, h, start, destination): |
| 131 | + nodes = {start, destination} |
| 132 | + for x, y in product(range(w), range(h)): |
| 133 | + if grid[(x, y)] != '#': |
| 134 | + adj = set(p for p in adjacent((x, y)) if grid[p] != '#') |
| 135 | + if len(adj) > 2: |
| 136 | + nodes.add((x, y)) |
| 137 | + return nodes |
| 138 | + |
| 139 | +def hike_length(weights, x): |
| 140 | + return sum(weights[(min(x[i], x[i + 1]), max(x[i], x[i + 1]))] for i in range(len(x) - 1)) |
| 141 | + |
| 142 | +def route_using_networkx(lines): |
| 143 | + weights, start, destination = find_graph(lines) |
| 144 | + |
| 145 | + # g = nx.from_edgelist(weights.keys()) |
| 146 | + g = nx.Graph() |
| 147 | + for e, w in weights.items(): |
| 148 | + g.add_edge(e[0], e[1], weight=w) |
| 149 | + |
| 150 | + longest = max(nx.all_simple_paths(g, start, destination), key=lambda a: hike_length(weights, a)) |
| 151 | + pe = list(nx.utils.pairwise(longest)) |
| 152 | + |
| 153 | + visual = False |
| 154 | + if visual: |
| 155 | + plot_graph(g, pe) |
| 156 | + |
| 157 | + ll = hike_length(weights, longest) |
| 158 | + return ll |
| 159 | + |
| 160 | +def plot_graph(g, pe): |
| 161 | + # pos = nx.spring_layout(g, seed=seed) |
| 162 | + pos = nx.kamada_kawai_layout(g) |
| 163 | + nx.draw_networkx_nodes(g, pos) |
| 164 | + nx.draw_networkx_edges(g, pos, width=3) |
| 165 | + if pe: |
| 166 | + nx.draw_networkx_edges(g, pos, edgelist=pe, edge_color="red", width=6) |
| 167 | + nx.draw_networkx_labels(g, pos, font_size=20, font_family="sans-serif") |
| 168 | + edge_labels = nx.get_edge_attributes(g, "weight") |
| 169 | + nx.draw_networkx_edge_labels(g, pos, edge_labels) |
| 170 | + ax = plt.gca() |
| 171 | + ax.margins(0.08) |
| 172 | + plt.axis("off") |
| 173 | + plt.tight_layout() |
| 174 | + plt.show() |
| 175 | + |
| 176 | +def main(): |
| 177 | + puzzle_input = adventofcode.read_input(23) |
| 178 | + adventofcode.answer(0, 94, part1(t1)) |
| 179 | + adventofcode.answer(1, 2310, part1(puzzle_input)) |
| 180 | + adventofcode.answer(0, 154, part2(t1)) |
| 181 | + adventofcode.answer(2, 6738, part2(puzzle_input)) |
| 182 | + |
| 183 | +if __name__ == '__main__': |
| 184 | + import doctest |
| 185 | + |
| 186 | + doctest.testmod() |
| 187 | + main() |
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