luogu 4147 玉蟾宫 悬线DP

Code:

#include<bits/stdc++.h>
using namespace std;
#define setIO(s) freopen(s".in","r",stdin)
#define maxn 1002
int n,m;
int mk[maxn][maxn],l[maxn][maxn],r[maxn][maxn],up[maxn][maxn];
char str[maxn];
int main()
{
    // setIO("input");
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i)
    {
        for(int j=1;j<=m;++j)
        {
            scanf("%s",str+1);
            if(str[1]=='F') mk[i][j]=up[i][j]=1,l[i][j]=r[i][j]=j;
        }
    }
    for(int i=1;i<=n;++i) for(int j=2;j<=m;++j) if(mk[i][j]&&mk[i][j-1]) l[i][j]=l[i][j-1];
    for(int i=1;i<=n;++i) for(int j=m-1;j>=1;--j) if(mk[i][j]&&mk[i][j+1]) r[i][j]=r[i][j+1];
    int ans=0;
    for(int i=1;i<=n;++i)
    {
        for(int j=1;j<=m;++j)
        {
            if(i>1 && mk[i][j] && mk[i-1][j])
            {
                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]);
            }
            ans=max(ans, (r[i][j]-l[i][j]+1)*up[i][j]);
        }
    }
    printf("%d\n",ans*3);
    return 0;
}