695. 岛屿的最大面积

class Solution {
public:
    int dir[4][2]={1,0,0,1,-1,0,0,-1};
    int ans=0;
    void bfs(vector >&flag,int x,int y,vector>& grid){
        queue >q;
        q.push({x,y});
        flag[x][y]=true;
        int cnt=0;
        cnt++;
        while(!q.empty()){
            pairp=q.front();
            q.pop();
            int nx=p.first;
            int ny=p.second;
            for(int i=0;i<4;i++){
                int xx=nx+dir[i][0];
                int yy=ny+dir[i][1];
                if(xx<0||yy<0||xx>=grid.size()||yy>=grid[0].size())continue;
                if(flag[xx][yy]==false&&grid[xx][yy]==1){
                    q.push({xx,yy});
                    flag[xx][yy]=true;
                    cnt++;
                }
            }
        }
        if(cnt>ans)ans=cnt;
    }
    int maxAreaOfIsland(vector>& grid) {
        int n=grid.size();
        int m=grid[0].size();
        vector >flag=vector >(n,vector(m,false));
        for(int i=0;i