【HDOJ】2830 Matrix Swapping II

简单DP。

 /* 2830 */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 using namespace std;

 const int maxn = ;
 char M[maxn][maxn];
 int mlen[maxn][maxn];
 int cnt[maxn];
 int n, m;

 int main() {
     int i, j, k;
     int ans, mx, tmp;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     while (scanf("%d %d", &n, &m) != EOF) {
         for (i=; i<=n; ++i) {
             scanf("%s", M[i]+);
             for (j=; j<=m; ++j)
                 M[i][j] -= '';
         }
         for (j=; j<=m; ++j) {
             mlen[j][] = ;
             for (i=; i<=n; ++i) {
                 if (M[i][j])
                     mlen[j][i] = mlen[j][i-]+;
                 else
                     mlen[j][i] = ;
             }
         }

         ans = ;
         for (i=; i<=n; ++i) {
             memset(cnt, , sizeof(cnt));
             mx = -;
             for (j=; j<=m; ++j) {
                 ++cnt[mlen[j][i]];
                 mx = max(mx, mlen[j][i]);
             }
             for (j=mx; j>; --j) {
                 ans = max(ans, cnt[j]*j);
                 cnt[j-] += cnt[j];
             }
         }
         printf("%d\n", ans);
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }