HDU 1728 逃离迷宫（BFS）

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 #include <queue>
 6 using namespace std;
 7 
 8 const int MAXN = 110;
 9 
10 struct Node {
11     int f, x, y;
12     Node() {}
13     Node(int f, int x, int y):
14         f(f), x(x), y(y) {}
15 };
16 
17 int fx[] = {-1, 0, 1, 0};
18 int fy[] = {0, 1, 0, -1};
19 
20 int dis[4][MAXN][MAXN];
21 char mat[MAXN][MAXN];
22 int T, n, m;
23 int k, x1, y1, x2, y2;
24 
25 bool solve() {
26     memset(dis, 0x3f, sizeof(dis));
27     queue<Node>* pre = new queue<Node>();
28     queue<Node>* cur = new queue<Node>();
29     int step = 0;
30     for(int i = 0; i < 4; ++i) pre->push(Node(i, x1, y1));
31     for(int i = 0; i < 4; ++i) dis[i][x1][y1] = 0;
32     while(step <= k) {
33         Node t = pre->front(); pre->pop();
34         if(dis[t.f][t.x][t.y] != step) continue;
35         if(t.x == x2 && t.y == y2) return true;
36         for(int i = 0; i < 4; ++i) {
37             if((t.f + 2) % 4 == i) continue;
38             int x = t.x + fx[i], y = t.y + fy[i], d = dis[t.f][t.x][t.y] + (t.f != i);
39             if(mat[x][y] == ‘.‘ && d < dis[i][x][y]) {
40                 dis[i][x][y] = d;
41                 if(t.f == i) pre->push(Node(i, x, y));
42                 else cur->push(Node(i, x, y));
43             }
44         }
45         if(pre->empty()) {
46             step++;
47             if(cur->empty()) break;
48             swap(pre, cur);
49         }
50     }
51     return false;
52 }
53 
54 int main() {
55     scanf("%d", &T);
56     while(T--) {
57         scanf("%d%d", &n, &m);
58         memset(mat, 0, sizeof(mat));
59         for(int i = 1; i <= n; ++i) scanf("%s", &mat[i][1]);
60         scanf("%d%d%d%d%d", &k, &y1, &x1, &y2, &x2);
61         puts(solve() ? "yes" : "no");
62     }
63 }