USACO 5.3 Big Barn(DP）

最大子矩阵问题，USACO上貌似好几个把。。

 1 /*
 2 ID: cuizhe
 3 LANG: C++
 4 TASK: bigbrn
 5 */
 6 #include <iostream>
 7 #include <cstring>
 8 #include <cstdio>
 9 #include <cstdlib>
10 using namespace std;
11 int dp[1001][1001],r[1001][1001],c[1001][1001];
12 bool o[1001][1001];
13 int main()
14 {
15     int n,m,x,y,maxz,i,j;
16     freopen("bigbrn.in","r",stdin);
17     freopen("bigbrn.out","w",stdout);
18     scanf("%d%d",&n,&m);
19     for(i = 1;i <= m;i ++)
20     {
21         scanf("%d%d",&x,&y);
22         o[x][y] = 1;
23     }
24     for(x = 1;x <= n;x ++)
25     {
26         for(y = 1;y <= n;y ++)
27         {
28             if(o[x][y])
29             {
30                 r[x][y] = 0;
31                 c[x][y] = 0;
32                 dp[x][y] = 0;
33             }
34             else
35             {
36                 r[x][y] = r[x-1][y] + 1;
37                 c[x][y] = c[x][y-1] + 1;
38                 dp[x][y] = min(min(r[x][y],c[x][y]),dp[x-1][y-1]+1);
39             }
40         }
41     }
42     maxz = 0;
43     for(i = 1;i <= n;i ++)
44     {
45         for(j = 1;j <= n;j ++)
46         {
47             maxz =max(dp[i][j],maxz);
48         }
49     }
50     printf("%d\n",maxz);
51     return 0;
52 }

 

posted @ 2013-05-27 18:15  Naix_x  阅读(152)  评论(0)  编辑  收藏  举报