【HDOJ】1242 Rescue

BFS+优先级队列。

 1 #include <iostream>

 2 #include <cstdio>

 3 #include <cstring>

 4 #include <queue>

 5 using namespace std;

 6

 7 #define MAXNUM 205

 8

 9 typedef struct node_st {

10     int x, y ,t;

11     node_st() {}

12     node_st(int xx, int yy, int tt) {

13         x = xx; y = yy; t = tt;

14     }

15     friend bool operator < (node_st a, node_st b) {

16         return a.t > b.t;

17     }

18 } node_st;

19

20 int n, m;

21 char map[MAXNUM][MAXNUM];

22 char visit[MAXNUM][MAXNUM];

23 int direct[4][2] = {{1,0},{-1,0},{0,-1},{0,1}};

24

25 int bfs(int x, int y) {

26     priority_queue<node_st> que;

27     node_st node;

28     int i, t;

29

30     que.push(node_st(x, y, 0));

31     memset(visit, 0, sizeof(visit));

32     visit[x][y] = 1;

33

34     while ( !que.empty() ) {

35         node = que.top();

36         if (map[node.x][node.y] == ‘a‘)

37             return node.t;

38         que.pop();

39         t = node.t + 1;

40         for (i=0; i<4; ++i) {

41             x = node.x + direct[i][0];

42             y = node.y + direct[i][1];

43             if (x<0 || x>=n || y<0 || y>=m)

44                 continue;

45             if (visit[x][y] || map[x][y]==‘#‘)

46                 continue;

47             if (map[x][y] == ‘x‘)

48                 que.push(node_st(x,y,t+1));

49             else

50                 que.push(node_st(x,y,t));

51             visit[x][y] = 1;

52         }

53     }

54

55     return -1;

56 }

57

58 int main() {

59     int i, j, t;

60     int begx, begy;

61

62     while (scanf("%d %d", &n, &m) != EOF) {

63         for (i=0; i<n; ++i) {

64             scanf("%s", map[i]);

65             for (j=0; j<m; ++j) {

66                 if (map[i][j] == ‘r‘) {

67                     begx = i;

68                     begy = j;

69                 }

70             }

71         }

72         t = bfs(begx, begy);

73         if (t == -1)

74             printf("Poor ANGEL has to stay in the prison all his life.\n");

75         else

76             printf("%d\n", t);

77     }

78     return 0;

79 }