UVA1330 City Game

利用网格图上空白的方格上建一个矩形的建筑。问地区中建筑物的最大面积

 递推(dp)

#include <iostream>
#include <cstring>
#include <sstream>
using namespace std;
const int N=1e3+2;
char a[N][N];
 int n,m,up[N][N],L[N][N],R[N][N];

 void solve(){
 	int i,j;
 	cin>>n>>m;
 	memset(up,0,sizeof up);
 	memset(L,0,sizeof L);
 	memset(R,0,sizeof R);
 	
 	for(i=1;i<=n;i++)
 	 for(j=1;j<=m;j++){
 	 	cin>>a[i][j];
 	 	if(a[i][j]=='F'){
 	 		L[i][j]=j ; R[i][j]=j; up[i][j]=1;
 	 	}
 	 }
 	for(i=1;i<=n;i++){
 	 	for(j=2;j<=m;j++)
	 	 	if(a[i][j]=='F'&&a[i][j-1]=='F')
	 	 		L[i][j] =L[i][j-1]; 
 	 	
 	 	for(j=m-1;j>0;j--)
 	 		if(a[i][j]=='F'&&a[i][j+1]=='F') 
 	 			R[i][j] =R[i][j+1];
 	}
 	for(i=2;i<=n;i++)
 	 	for(j=1;j<=m;j++){
 	 		if(a[i][j]=='F'&&a[i-1][j]=='F'){
 	 			up[i][j]=up[i-1][j]+1;
 	 			L[i][j] =max(L[i][j],L[i-1][j]);
 	 			R[i][j] =min(R[i][j],R[i-1][j]);
 	 		}
 	 	}
 	int ans=0;
 	for(i=1;i<=n;i++)
 	 	for(j=1;j<=m;j++)
 	 		ans=max(ans,(R[i][j]-L[i][j]+1)*up[i][j]);
 	cout<<3*ans<<endl;
 }
 signed main(){
 	int tes;
 	cin>>tes; 
 	while(tes--) solve();
 }