[洛谷P4147]玉蟾宫

题目大意：最大全一子矩阵

题解：单调栈

卡点：果然我还是不会单调栈，长宽写错

C++ Code：

#include <cstdio>
#define maxn 1010
struct node {
	int len, h;
	inline node (int __len = 0, int __h = 0) {len = __len, h = __h;}
} S[maxn];
inline int max(int a, int b) {return a > b ? a : b;}

int top;
int n, m, ans;
char p[maxn][maxn];
int s[maxn][maxn];
int main() {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			scanf("%1s", p[i] + j);
			if (p[i][j] == 'F') s[i][j] = s[i - 1][j] + 1;
		}
	}
	for (int i = 1; i <= n; i++) {
		S[top = 1] = node(1, s[i][1]);
		for (int j = 2; j <= m; j++) {
			int len = 0;
			while (top && s[i][j] <= S[top].h) {
				len += S[top].len;
				ans = max(ans, len * S[top].h);
				top--;
			}
			S[++top] = node(len + 1, s[i][j]);
		}
		int len = 0;
		while (top) {
			len += S[top].len;
			ans = max(ans, len * S[top].h);
			top--;
		}
	}
	printf("%d\n", ans * 3);
	return 0;
}