bzoj3039 joyoi1939 玉蟾宫 悬线法

悬线法

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int n, m, ans=0, h[1005][1005], l[1005][1005], r[1005][1005];
bool a[1005][1005];
char s[15];
int main(){
	cin>>n>>m;
	for(int i=1; i<=n; i++)
		for(int j=1; j<=m; j++){
			scanf("%s", s);
			a[i][j] = s[0]=='F';
		}
	for(int i=1; i<=n; i++){
		int x=1;
		for(int j=1; j<=m; j++)
			if(a[i][j])	l[i][j] = x;
			else	l[i][j] = 1, x = j + 1;
		x = m;
		for(int j=m; j>=1; j--)
			if(a[i][j])	r[i][j] = x;
			else	r[i][j] = m, x = j - 1;
	}
	for(int i=1; i<=m; i++)	l[0][i] = 1, r[0][i] = m;
	for(int i=1; i<=n; i++)
		for(int j=1; j<=m; j++)
			if(a[i][j]){
				h[i][j] = h[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)*h[i][j]);
			}
	cout<<ans*3<<endl;
	return 0;
}