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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();
 }