【HDOJ】1484 Basic wall maze

BFS。

 1 /* 1484 */
 2 #include <iostream>
 3 #include <queue>
 4 #include <string>
 5 #include <cstdio>
 6 #include <cstring>
 7 #include <algorithm>
 8 using namespace std;
 9
10 typedef struct {
11     int x, y;
12     string s;
13 } node_t;
14
15 bool m[8][8][4];
16 bool visit[8][8];
17 char ds[5] = "NSWE";
18 int dir[4][2] = {
19     -1,0,1,0,0,-1,0,1
20 };
21
22 const int n = 6;
23 int bx, by, ex, ey;
24 string ans;
25
26 void bfs() {
27     int x = bx, y = by;
28     int i, j, k;
29     queue<node_t> Q;
30     string s;
31     node_t nd, tmp;
32
33     memset(visit, false, sizeof(visit));
34     visit[x][y] = true;
35     nd.x = x;
36     nd.y = y;
37     nd.s = "";
38     Q.push(nd);
39
40     while (!Q.empty()) {
41         nd = Q.front();
42         Q.pop();
43         for (i=0; i<4; ++i) {
44             if (m[nd.x][nd.y][i])
45                 continue;
46             x = nd.x + dir[i][0];
47             y = nd.y + dir[i][1];
48             if (x<=0 || x>6 || y<=0 || y>6 || visit[x][y])
49                 continue;
50             visit[x][y] = true;
51             tmp.x = x;
52             tmp.y = y;
53             tmp.s = nd.s + ds[i];
54             if (x==ex && y==ey) {
55                 ans = tmp.s;
56                 return ;
57             }
58             Q.push(tmp);
59         }
60     }
61 }
62
63 int main() {
64     int i, j, k;
65     int x, y;
66     int a, b, c, d;
67
68     #ifndef ONLINE_JUDGE
69         freopen("data.in", "r", stdin);
70     #endif
71
72     while (scanf("%d %d",&by,&bx)!=EOF && (by||bx)) {
73         scanf("%d %d", &ey, &ex);
74         memset(m, false, sizeof(m));
75         for (i=0; i<3; ++i) {
76             scanf("%d%d%d%d", &a,&b,&c,&d);
77             if (b == d) {
78                 // north & south need to mask
79                 for (y=a+1; y<=c; ++y) {
80                     m[b][y][1] = true;
81                     m[b+1][y][0] = true;
82                 }
83             } else {
84                 // west & east need to mask
85                 for (x=b+1; x<=d; ++x) {
86                     m[x][a][3] = true;
87                     m[x][a+1][2] = true;
88                 }
89             }
90         }
91         bfs();
92         printf("%s\n", ans.c_str());
93     }
94
95     return 0;
96 }