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uva 1330 City Game (最大子矩阵)

空白最多的最大子矩阵:

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 1005;

int mat[maxn][maxn],up[maxn][maxn],left[maxn][maxn],right[maxn][maxn];
int main()
{
    int t;
    scanf("%d",&t);
    while(t--){
        int m,n;
        scanf("%d%d",&m,&n);
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                char ch=getchar();
                while(ch!='F'&&ch!='R') ch=getchar();
                mat[i][j] = ch=='F'?0:1;
            }
        }
        int ans=0;
        for(int i=0;i<m;i++){
            int lo = -1,ro = n;
            for(int j=0;j<n;j++){
                if(mat[i][j]==1){
                    up[i][j]=left[i][j]=0;
                    lo = j;
                }
                else{
                    up[i][j]=i==0?1:up[i-1][j]+1;
                    left[i][j]=i==0?lo+1:max(lo+1,left[i-1][j]);
                }
            }
            for(int j=n-1;j>=0;j--){
                if(mat[i][j]==1){
                    right[i][j]=n;
                    ro=j;
                }
                else{
                    right[i][j]=i==0?ro-1:min(ro-1,right[i-1][j]);
                    int temp = up[i][j]*(right[i][j]-left[i][j]+1);
                    ans=max(ans,temp);
                }
            }

        }
        printf("%d\n",ans*3);
    }
    return 0;
}


uva 1330 City Game (最大子矩阵)