[hdu][4003][Find Metal Mineral]

题目：http://acm.hdu.edu.cn/showproblem.php?pid=4003

#include <stdio.h>
#include <string.h>
#include <algorithm>

#define clr(a,b) memset(a,b,sizeof(a))
using namespace std;

const int N = 10000+10;
const int M = 20000+10;

int n, e, s, k;
int he[N];
int ev[M], ew[M], nxt[M];
int dp[N][11];

void init()
{
    e = 0; clr(he, -1);
}

void add(int u, int v, int w)
{
    ev[e]=v; ew[e]=w; nxt[e]=he[u]; he[u]=e++;
    ev[e]=u; ew[e]=w; nxt[e]=he[v]; he[v]=e++;
}

void dfs(int u, int r)
{
    for (int i=he[u]; i!=-1; i=nxt[i])
    {
        if (ev[i] == r)continue;
        dfs(ev[i], u);
    }
    for (int i=he[u]; i!=-1; i=nxt[i])
    {
        int v = ev[i];
        if (v == r)continue;
        for (int j=k; j>=0; j--)
        {
            dp[u][j]+=dp[v][0]+2*ew[i];
            for (int t=1; t<=j; t++)
                dp[u][j]=min(dp[u][j], dp[u][j-t]+dp[v][t]+t*ew[i]);
        }
    }
}

int main()
{
    //freopen("D:/a.txt", "r", stdin);
    while (~scanf("%d%d%d", &n, &s, &k))
    {
        init();
        for (int i=1; i<n; i++)
        {
            int u, v, w;
            scanf("%d%d%d", &u, &v, &w);
            add(u, v, w);
        }
        clr(dp, 0);
        dfs(s, 0);
        printf("%d\n", dp[s][k]);
    }
    return 0;
}