51nod 1158 全是1的最大子矩阵

题目分类是单调栈，我这里直接用与解最大子矩阵类似的办法水过了。。。

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cmath>
 4 #include<algorithm>
 5 #define CLR(a,b) memset((a),(b),sizeof((a)))
 6 using namespace std;
 7 const int N = 501;
 8 const int inf = 0x3f3f3f3f;
 9 int n, m;
10 int dp[N][N];
11 int main(){
12     int i, j, k, ans, x, h;
13     scanf("%d%d", &m, &n);
14     CLR(dp, 0);
15     for(i = 1; i <= n; ++i){
16         for(j = 1; j <= m; ++j){
17             scanf("%d", &x);
18             if(x) dp[i][j] = x + dp[i-1][j];
19         }
20     }
21     ans = 0;
22     for(i = 1; i <= m; ++i){
23         for(j = 1 ; j <= n; ++j){
24             h = inf;
25             for(k = i; k <= m; ++k){
26                 h = min(h, dp[j][k]);
27                 if(h == 0) break;
28                 ans = max(ans, (k-i+1) * h);
29             }
30         }
31     }
32     printf("%d
", ans);
33     return 0;
34 }

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