66 lines
1.2 KiB
C++
66 lines
1.2 KiB
C++
#include<stdio.h>
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#include<algorithm>
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#include<string.h>
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#include<iostream>
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using namespace std;
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const int MAXN=10010;
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struct Node
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{
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int to;
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int next;
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int cost;
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}edge[MAXN*2];
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int head[MAXN];
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int tol;
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int dp[MAXN][11];
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void init()
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{
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memset(head,-1,sizeof(head));
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tol=0;
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memset(dp,0,sizeof(dp));
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}
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void add(int a,int b,int val)
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{
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edge[tol].to=b;
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edge[tol].cost=val;
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edge[tol].next=head[a];
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head[a]=tol++;
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edge[tol].to=a;
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edge[tol].cost=val;
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edge[tol].next=head[b];
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head[b]=tol++;
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}
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int N,K;
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void dfs(int u,int pre)
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{
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for(int i=head[u];i!=-1;i=edge[i].next)
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{
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int v=edge[i].to;
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if(v==pre)continue;
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dfs(v,u);
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for(int k=K;k>=0;k--)
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{
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dp[u][k]+=dp[v][0]+2*edge[i].cost;
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for(int j=1;j<=k;j++)
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dp[u][k]=min(dp[u][k],dp[u][k-j]+dp[v][j]+j*edge[i].cost);
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}
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}
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}
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int main()
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{
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int S;
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int a,b,val;
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while(scanf("%d%d%d",&N,&S,&K)!=EOF)
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{
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init();
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for(int i=1;i<N;i++)
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{
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scanf("%d%d%d",&a,&b,&val);
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add(a,b,val);
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}
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dfs(S,-1);
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printf("%d\n",dp[S][K]);
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}
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return 0;
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}
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