01迷宫

https://www.luogu.org/problemnew/show/P1141

题解：不知道为什么只要是连通块就行了

BFS

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
typedef __int128 lll;
const int N=1000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,x,y;
int a[N][N];
int vis[N][N];
int b[][2]={1,0,0,1,-1,0,0,-1};
string str;
struct node{
    int x,y;
}s,f,tmp;
queue<node>q;
int cnt=0;

int ans[N*N];
void bfs(){
    s.x=x;
    s.y=y;
    while(!q.empty())
        q.pop();
    q.push(s);
    //memset(vis,0,sizeof(vis));
    vis[x][y]=cnt;
    ans[cnt]=1;
    while(!q.empty()){
        f=q.front();
        q.pop();
        for(int i=0;i<4;i++){
            tmp.x=f.x+b[i][0];
            tmp.y=f.y+b[i][1];
            if(vis[tmp.x][tmp.y])
                continue;
            if(0<tmp.x&&tmp.x<=n&&0<tmp.y&&tmp.y<=n&&a[f.x][f.y]!=a[tmp.x][tmp.y]){
                ans[cnt]++;
                vis[tmp.x][tmp.y]=cnt;
                q.push(tmp);
            }
        }
    }
}
int main()
{
#ifdef DEBUG
	freopen(\"input.in\", \"r\", stdin);
	//freopen(\"output.out\", \"w\", stdout);
#endif
    //ios::sync_with_stdio(false);
    scanf(\"%d%d\",&n,&m);
    for(int i=1;i<=n;i++){
        cin>>str;
        for(int j=1;j<=n;j++){
            a[i][j]=str[j-1]-\'0\';
        }
    }
    while(m--){
        scanf(\"%d%d\",&x,&y);
        if(vis[x][y]){
            printf(\"%d\\n\",ans[vis[x][y]]);
            continue;
        }
        cnt++;
        bfs();
        printf(\"%d\\n\",ans[vis[x][y]]);
        //cout << ans+1 << endl;
    }
    //cout << \"Hello world!\" << endl;
    return 0;
}