hdu 4003 树形dp+分组背包 2011大连赛区网络赛C

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<queue>
 7 #include<map>
 8 using namespace std;
 9 #define MOD 1000000007
10 const int INF=0x3f3f3f3f;
11 const double eps=1e-5;
12 typedef long long ll;
13 #define cl(a) memset(a,0,sizeof(a))
14 #define ts printf("*****\n");
15 const int MAXN=10010;
16 int dp[MAXN][11],val[MAXN],head[MAXN];
17 int n,m,tt,tot;
18 struct Edge
19 {
20     int to,next,val;
21 }edge[MAXN*2];
22 void addedge(int u,int v,int w)
23 {
24     edge[tot].to=v;
25     edge[tot].next=head[u];
26     edge[tot].val=w;
27     head[u]=tot++;
28 }
29 void init()
30 {
31     memset(head,-1,sizeof(head));
32     tot=0;
33     memset(dp,0,sizeof(dp));
34 }
35 void dfs(int u,int pre)
36 {
37     for(int i=head[u];i!=-1;i=edge[i].next)
38     {
39         int v=edge[i].to;
40         if(v==pre)  continue;
41         dfs(v,u);
42         for(int j=m;j>=0;j--)
43         {
44             dp[u][j]+=dp[v][0]+2*edge[i].val;
45             for(int k=1;j-k>=0;k++)
46             {
47                 dp[u][j]=min(dp[u][j],dp[u][j-k]+dp[v][k]+k*edge[i].val);
48             }
49         }
50     }
51 }
52 int main()
53 {
54     int i,j,k;
55     #ifndef ONLINE_JUDGE
56     freopen("1.in","r",stdin);
57     #endif
58     int st;
59     int a,b,val;
60     while(scanf("%d%d%d",&n,&st,&m)!=EOF)
61     {
62         init();
63         for(i=1;i<n;i++)
64         {
65             scanf("%d%d%d",&a,&b,&val);
66             addedge(a,b,val);
67             addedge(b,a,val);
68         }
69         dfs(st,-1);
70         printf("%d\n",dp[st][m]);
71     }
72 }