今日才真正懂了BFS

head=1;
tail=1;
que[head]=1;
while(head<=tail){
    for(i=2;i<=n;i++){
        if(map[que[head]][i]==1 && dist[i]==0){
            que[++tail]=i;
            dist[i]=dist[que[head]]+1;
        }
    }
    head++;
}