pku2378 Tree Cutting

http://poj.org/problem?id=2378

树状DP

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <vector>
 4 #include <set>
 5 
 6 #define N 10010
 7 
 8 using namespace std;
 9 
10 vector<int> a[N];
11 set<int> set1;
12 set<int>::iterator it;
13 
14 int n, father[N] = {0};
15 
16 int dfs(int x)
17 {
18     int i, j, flag = 0, sum = 1, temp;
19     //printf("%d: ( ", x);
20     for(i=0; i<a[x].size(); i++)
21     {
22         j = a[x][i];
23         if(!father[j])
24         {
25             father[j] = x;
26             temp = dfs(j);
27             sum += temp;
28             if(temp > n/2)
29             {
30                 flag = 1;
31             }
32         }
33     }
34     if(n - sum > n/2)
35     {
36         flag = 1;
37     }
38     if(flag == 0)
39     {
40         set1.insert(x);
41     }
42     //printf(" %d) ", dp[x]);
43     return sum;
44 }
45 
46 int main()
47 {
48     int i, x, y;
49     scanf("%d", &n);
50     for(i=1; i<=n-1; i++)
51     {
52         scanf("%d%d", &x, &y);
53         a[x].push_back(y);
54         a[y].push_back(x);
55     }
56     father[1] = 1;
57     dfs(1);
58     for(it=set1.begin(); it!=set1.end(); it++)
59     {
60         printf("%d\n", *it);
61     }
62     return 0;
63 }

 

posted @ 2013-03-27 16:32  Yuan1991  阅读(135)  评论(0)  编辑  收藏  举报