2017 Multi-University Training Contest 3 hdu 6060

HDU 6060

思路：

AC代码：

#include "iostream"
#include "string.h"
#include "stack"
#include "queue"
#include "string"
#include "vector"
#include "set"
#include "map"
#include "algorithm"
#include "stdio.h"
#include "math.h"
#pragma comment(linker, "/STACK:102400000,102400000")
#define ll long long
#define endl ("
")
#define bug(x) cout<<x<<" "<<"UUUUU"<<endl;
#define mem(a,x) memset(a,x,sizeof(a))
#define mp(x,y) make_pair(x,y)
#define pb(x) push_back(x)
#define ft (frist)
#define sd (second)
#define lrt (rt<<1)
#define rrt (rt<<1|1)
using namespace std;
const long long INF = 1e18+1LL;
const int inf = 1e9+1e8;
const int N=1e6+100;
const ll mod=1e9+7;

ll siz[N],head[N],nex[N<<1],to[N<<1],wi[N<<1],tot,n,k;
ll ans;
void dfs(int u, int f, ll w){
    siz[u]=1;
    for(int i=head[u]; i!=-1; i=nex[i]){
        int v=to[i];
        if(v==f) continue;
        dfs(v,u,wi[i]);
        siz[u]+=siz[v];
    }
    if(siz[u]>=k) ans+=w*k;
    else ans+=w*siz[u];
}
void add(int u, int v, int w){
    to[tot]=v;
    nex[tot]=head[u];
    wi[tot]=w;
    head[u]=tot++;
}
int main(){
    while(scanf("%d %d",&n, &k)!=EOF){
        mem(head,-1),tot=0;
        int u,v;
        ll w;
        for(int i=1; i<n; ++i){
            scanf("%d %d %lld", &u, &v, &w);
            add(u,v,w);
            add(v,u,w);
        }
        ans=0;
        dfs(1,1,0);
        printf("%lld
",ans);
    }
    return 0;
}