标签：
Given Joe‘s location in the maze and which squares of the maze are on fire, you must determine whether Joe can exit the maze before the fire reaches him, and how fast he can do it.
Joe and the fire each move one square per minute, vertically or horizontally (not diagonally). The fire spreads all four directions from each square that is on fire. Joe may exit the maze from any square that borders the edge of the maze. Neither Joe nor the fire may enter a square that is occupied by a wall.
2 4 4 #### #JF# #..# #..# 3 3 ### #J. #.F
3 IMPOSSIBLE
解题：bfs...让火先走，再人走。。判断走出去的是人还是火
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <queue> 5 using namespace std; 6 const int maxn = 1010; 7 char mp[maxn][maxn]; 8 bool vis[maxn][maxn]; 9 int n,m; 10 struct node{ 11 int x,y,t; 12 bool isFire; 13 node(int a = 0,int b = 0,int c = 0,bool isfire = true){ 14 x = a; 15 y = b; 16 t = c; 17 isFire = isfire; 18 } 19 }; 20 queue<node>q; 21 bool isIn(int x,int y){ 22 return x < n && x >= 0 && y < m && y >= 0; 23 } 24 int bfs(){ 25 static const int dir[4][2] = {-1,0,1,0,0,-1,0,1}; 26 while(!q.empty()){ 27 node now = q.front(); 28 q.pop(); 29 for(int i = 0; i < 4; ++i){ 30 int tx = now.x + dir[i][0]; 31 int ty = now.y + dir[i][1]; 32 if(isIn(tx,ty)){ 33 if(!vis[tx][ty]){ 34 vis[tx][ty] = true; 35 q.push(node(tx,ty,now.t+1,now.isFire)); 36 } 37 }else if(!now.isFire) return now.t+1; 38 } 39 } 40 return -1; 41 } 42 int main(){ 43 int kase,px,py; 44 scanf("%d",&kase); 45 while(kase--){ 46 scanf("%d %d",&n,&m); 47 memset(vis,false,sizeof(vis)); 48 while(!q.empty()) q.pop(); 49 for(int i = 0; i < n; ++i){ 50 scanf("%s",mp[i]); 51 for(int j = 0; j < m; ++j){ 52 if(mp[i][j] == ‘F‘){ 53 vis[i][j] = true; 54 q.push(node(i,j,0,true)); 55 }else if(mp[i][j] == ‘#‘) vis[i][j] = true; 56 else if(mp[i][j] == ‘J‘) vis[px = i][py = j] = true; 57 } 58 } 59 q.push(node(px,py,0,false)); 60 int ans = bfs(); 61 if(ans == -1) puts("IMPOSSIBLE"); 62 else printf("%d\n",ans); 63 } 64 return 0; 65 } 66 /* 67 2 68 4 4 69 #### 70 #JF# 71 #..# 72 #..# 73 3 3 74 ### 75 #J. 76 #.F 77 78 */
标签：
原文地址：http://www.cnblogs.com/crackpotisback/p/4330943.html
