[poj1987]Distance Statistics

同[poj1741]Tree。。。

（不过说好的数据范围呢。。。）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
using namespace std;

char s[10];
int n,m,k;
const int N=100000;
int h[N],to[N],r[N],w[N],ans,tot,num,root,deep[N],d[N],sz[N],f[N],v[N],sum;
void ins(int u,int v,int z){
    to[tot]=v;
    w[tot]=z;
    r[tot]=h[u];
    h[u]=tot++;
}

void getDeep(int x,int fa){
    deep[++num]=d[x];
    for(int i=h[x];i!=-1;i=r[i]){
        if(!v[to[i]]&&to[i]!=fa){
            d[to[i]]=d[x]+w[i];
            getDeep(to[i],x);
        }
    }
}
void getRoot(int x,int fa){
    sz[x]=1;
    f[x]=0;
    for(int i=h[x];i!=-1;i=r[i]){
        if(!v[to[i]]&&to[i]!=fa){
            getRoot(to[i],x);
            sz[x]+=sz[to[i]];
            f[x]=max(f[x],sz[to[i]]);
        }
    }
    f[x]=max(f[x],sum-sz[x]);
    if(f[x]<f[root])root=x;
}
int calc(int x,int val,int t=0){
    d[x]=val;
    num=0;
    getDeep(x,0);
    sort(deep+1,deep+1+num);
    for(int l=1,r=num;l<r;){
        if(deep[l]+deep[r]<=k){t+=r-l;l++;}
        else r--;
    }
    return t;
}
void work(int x){
    ans+=calc(x,0);
    v[x]=1;
    for(int i=h[x];i!=-1;i=r[i]){
        if(!v[to[i]]){
            ans-=calc(to[i],w[i]);
            root=0;
            sum=sz[to[i]];
            getRoot(to[i],0);
            work(root);
        }
    }
}

int main(){
    memset(h,-1,sizeof(h));
    scanf("%d%d",&n,&m);
    for(int i=1,u,v,z;i<=m;i++)scanf("%d%d%d%s",&u,&v,&z,s),ins(u,v,z),ins(v,u,z);
    scanf("%d",&k);
    f[0]=0x3f3f3f3f;
    sum=n;
    getRoot(1,0);
    work(root);
    printf("%d\n",ans);
}