【HDOJ】2830 Matrix Swapping II

简单DP。

 1 /* 2830 */
 2 #include <iostream>
 3 #include <string>
 4 #include <map>
 5 #include <queue>
 6 #include <set>
 7 #include <stack>
 8 #include <vector>
 9 #include <algorithm>
10 #include <cstdio>
11 #include <cmath>
12 #include <ctime>
13 #include <cstring>
14 #include <climits>
15 #include <cctype>
16 #include <cassert>
17 using namespace std;
18 
19 const int maxn = 1005;
20 char M[maxn][maxn];
21 int mlen[maxn][maxn];
22 int cnt[maxn];
23 int n, m;
24 
25 int main() {
26     int i, j, k;
27     int ans, mx, tmp;
28     
29     #ifndef ONLINE_JUDGE
30         freopen("data.in", "r", stdin);
31         freopen("data.out", "w", stdout);
32     #endif
33     
34     while (scanf("%d %d", &n, &m) != EOF) {
35         for (i=1; i<=n; ++i) {
36             scanf("%s", M[i]+1);
37             for (j=1; j<=m; ++j)
38                 M[i][j] -= '0';
39         }
40         for (j=1; j<=m; ++j) {
41             mlen[j][0] = 0;
42             for (i=1; i<=n; ++i) {
43                 if (M[i][j])
44                     mlen[j][i] = mlen[j][i-1]+1;
45                 else
46                     mlen[j][i] = 0;
47             }
48         }
49         
50         ans = 0;
51         for (i=1; i<=n; ++i) {
52             memset(cnt, 0, sizeof(cnt));
53             mx = -1;
54             for (j=1; j<=m; ++j) {
55                 ++cnt[mlen[j][i]];
56                 mx = max(mx, mlen[j][i]);
57             }
58             for (j=mx; j>0; --j) {
59                 ans = max(ans, cnt[j]*j);
60                 cnt[j-1] += cnt[j];
61             }
62         }
63         printf("%d\n", ans);
64     }
65     
66     #ifndef ONLINE_JUDGE
67         printf("time = %d.\n", (int)clock());
68     #endif
69     
70     return 0;
71 }

 

posted on 2015-04-25 12:20  Bombe  阅读(188)  评论(0编辑  收藏  举报

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