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[105][105];
int vis[105][105];
int to[4][2]= {1,0,-1,0,0,1,0,-1};
int n,m,sx,sy,ex,ey,ans;

int check(int x,int y)
{
    if(x<0 || x>=n || y<0 || y>=m)
        return 1;
    if(vis[x][y] || map[x][y]=='#')
        return 1;
    return 0;
}

void bfs()
{
    int i;
    queue<node> Q;
    node a,next;
    a.x = sx;
    a.y = sy;
    a.step = 0;
    vis[a.x][a.y]=1;
    Q.push(a);
    while(!Q.empty())
    {
        a = Q.front();
        Q.pop();
        if(map[a.x][a.y]=='E')
        {
            ans = a.step;
            return ;
        }
        for(i = 0; i<4; i++)
        {
            next = a;
            next.x+=to[i][0];
            next.y+=to[i][1];
            if(check(next.x,next.y))
                continue;
            next.step=a.step+1;
            vis[next.x][next.y] = 1;
            Q.push(next);
        }
    }
    ans = -1;
}

int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&n,&m);
        int i,j;
        for(i = 0; i<n; i++)
            scanf("%s",map[i]);
        for(i = 0; i<n; i++)
        {
            for(j = 0; j<m; j++)
            {
                if(map[i][j]=='S')
                {
                    sx = i;
                    sy = j;
                }
            }
        }
        memset(vis,0,sizeof(vis));
        bfs();
        printf("%d
",ans);
    }

    return 0;
}