P1141 01迷宫

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#include<bits/stdc++.h>
using namespace std;

typedef pair<int,int> PII;
const int MAXN=1005;
int n,m;
char g[MAXN][MAXN];
int ans[MAXN][MAXN];
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};

void bfs(int startX,int startY)
{

    //初始化与启动
    ans[startX][startY]=1;
    queue<PII> q;
    q.push({startX,startY}); 
    vector<PII> team;
    team.push_back({startX,startY});

    while(!q.empty()){
        PII u=q.front();
        q.pop();

        for(int i=0;i<4;i++){
            int nx=u.first+dx[i];
            int ny=u.second+dy[i];

            if(nx>=1&&nx<=n&&ny<=n&&ny>=1
			&&ans[nx][ny]==0
			&&g[nx][ny]!=g[u.first][u.second]){
                ans[nx][ny]=1;
                team.push_back({nx,ny});
                q.push({nx,ny});
            }
        }
    }

    int count=team.size();
    for(auto p : team){
        ans[p.first][p.second]=count;
    }
}
    

int main()
{
    ios::sync_with_stdio(0),cin.tie(0);

    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>g[i][j];
        }
    }

    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(!ans[i][j]){
                bfs(i,j);
            }
        }
    }

    while(m--){
        int x,y;
        cin>>x>>y;
        cout<<ans[x][y]<<endl;
    }

    return 0;
}