1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
import { GridMaster } from "./GridMaster.ts";import { Heap } from "https://esm.sh/@datastructures-js/heap@4.1.2/src/heap.js";
export default function findShortestPath(master: GridMaster): number {    const key = JSON.stringify([0, 0]);    const grid: Map<string, number> = new Map();
    const end: number[] = [];    grid.set(key, -1);    dfs(0, 0, new Set<string>().add(key));    function dfs(        row: number,        col: number,        visited: Set<string>,    ) {        const key = JSON.stringify([row, col]);        if (master.isTarget()) {            end[0] = row;            end[1] = col;        }
        for (const [a, b, x, y] of directions) {            const nr = row + a;            const nc = col + b;            const str = JSON.stringify([nr, nc]);            if (!visited.has(str) && master.canMove(x)) {                visited.add(str);                const cost = master.move(x);                grid.set(str, cost);                dfs(nr, nc, visited);                grid.set(key, master.move(y));            }        }    }
    if (end.length === 0) return -1;    function bfs(        pos: [number, number][],        visited: Set<string>,    ): number {        const pq = new Heap<[number, number, number]>((a, b) => a[2] - b[2]);        pos.forEach(([r, c]) => pq.push([r, c, 0]));        while (!pq.isEmpty()) {            const [row, col, distance] = pq.pop();
            if (row === end[0] && col === end[1]) {                return distance;            }            for (const [a, b] of directions) {                const nr = row + a;                const nc = col + b;                const str = JSON.stringify([nr, nc]);                const cost = grid.get(str);                if (!visited.has(str) && cost) {                    visited.add(str);                    pq.push([nr, nc, cost + distance]);                }            }        }        return -1;    }    const distance = bfs([[0, 0]], new Set<string>().add(key));
    return distance;}const directions = [[0, -1, "L", "R"], [0, 1, "R", "L"], [-1, 0, "U", "D"], [    1,    0,    "D",    "U",]] as const;