另类题解

#include<bits/stdc++.h>
using namespace std;
char a;
int n,m,q[1010][1010],pre[1010][1010],best,num;
bool fsquare(int sx,int sy,int ex,int ey){
    int al=pre[ex][ey]-pre[sx-1][ey]-pre[ex][sy-1]+pre[sx-1][sy-1];
    return (al==(ex-sx+1)*(ey-sy+1));
}
void dfs(int sx,int sy,int ex,int ey){
    if(!fsquare(sx,sy,ex,ey)){return;}
    best=max(best,(ex-sx+1)*(ey-sy+1));
    dfs(sx,sy,ex+1,ey);
    if(sx==ex){dfs(sx,sy,ex,ey+1);}
}
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>a;
            if(a=='F'){
                q[i][j]=1;
            }
            pre[i][j]=pre[i-1][j]+pre[i][j-1]-pre[i-1][j-1]+q[i][j];
        }
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            dfs(i,j,i,j);
        }
    }
    cout<<best*3;
	return 0;
}```