模板 BFS

【模板】BFS

 #include <stdio.h>
 #include <string.h>
 #include <queue>
 using namespace std;

 struct node
 {
     int x,y,step;
 };

 char map[][];
 int vis[][];
 int to[][]= {,,-,,,,,-};
 int n,m,sx,sy,ex,ey,ans;

 int check(int x,int y)
 {
     if(x< || x>=n || y< || y>=m)
         return ;
     if(vis[x][y] || map[x][y]=='#')
         return ;
     return ;
 }

 void bfs()
 {
     int i;
     queue<node> Q;
     node a,next;
     a.x = sx;
     a.y = sy;
     a.step = ;
     vis[a.x][a.y]=;
     Q.push(a);
     while(!Q.empty())
     {
         a = Q.front();
         Q.pop();
         if(map[a.x][a.y]=='E')
         {
             ans = a.step;
             return ;
         }
         for(i = ; i<; i++)
         {
             next = a;
             next.x+=to[i][];
             next.y+=to[i][];
             if(check(next.x,next.y))
                 continue;
             next.step=a.step+;
             vis[next.x][next.y] = ;
             Q.push(next);
         }
     }
     ans = -;
 }

 int main()
 {
     int t;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d%d",&n,&m);
         int i,j;
         for(i = ; i<n; i++)
             scanf("%s",map[i]);
         for(i = ; i<n; i++)
         {
             for(j = ; j<m; j++)
             {
                 if(map[i][j]=='S')
                 {
                     sx = i;
                     sy = j;
                 }
             }
         }
         memset(vis,,sizeof(vis));
         bfs();
         printf("%d\n",ans);
     }

     return ;
 }