BZOJ 2152 Cong Coco (tree division), bzoj2152

BZOJ 2152 Cong Coco (tree division), bzoj2152

Address: BZOJ 2152
Find the number of vertices with the sum of three. The simplest point grouping.
The Code is as follows:

#include <iostream>#include <string.h>#include <math.h>#include <queue>#include <algorithm>#include <stdlib.h>#include <map>#include <set>#include <stdio.h>#include <time.h>using namespace std;#define LL __int64#define pi acos(-1.0)//#pragma comment(linker, "/STACK:1024000000")const int mod=1e9+7;const int INF=0x3f3f3f3f;const double eqs=1e-9;const int MAXN=20000+10;int head[MAXN], cnt, root, ans, min1;int siz[MAXN], ha[4], dep[MAXN], vis[MAXN];struct node{        int v, w, next;}edge[MAXN<<1];void add(int u, int v, int w){        edge[cnt].v=v;        edge[cnt].w=w;        edge[cnt].next=head[u];        head[u]=cnt++;}void init(){        memset(head,-1,sizeof(head));        cnt=ans=0;        memset(vis,0,sizeof(vis));}void getroot(int u, int fa, int s){        siz[u]=1;        int i, max1=0;        for(i=head[u];i!=-1;i=edge[i].next){                int v=edge[i].v;                if(v==fa||vis[v]) continue ;                getroot(v,u,s);                siz[u]+=siz[v];                max1=max(max1,siz[v]);        }        max1=max(max1,s-siz[u]);        if(min1>max1){                root=u;                min1=max1;        }}void getdep(int u, int fa){        ha[dep[u]%3]++;        siz[u]=1;        for(int i=head[u];i!=-1;i=edge[i].next){                int v=edge[i].v;                if(v==fa||vis[v])continue ;                dep[v]=dep[u]+edge[i].w;                getdep(v,u);                siz[u]+=siz[v];        }}int Cal(int u, int len){        dep[u]=len;        ha[0]=ha[1]=ha[2]=0;        getdep(u,-1);        return ha[0]*ha[0]+ha[1]*ha[2]*2;}void work(int u){        vis[u]=1;        ans+=Cal(u,0);        for(int i=head[u];i!=-1;i=edge[i].next){                int v=edge[i].v;                if(vis[v]) continue ;                ans-=Cal(v,edge[i].w);                min1=INF;                getroot(v,-1,siz[v]);                work(root);        }}int gcd(int x, int y){        return x==0?y:gcd(y%x,x);}int main(){        int n, u, v, w, i, j, _gcd;        while(scanf("%d",&n)!=EOF){                init();                for(i=1;i<n;i++){                        scanf("%d%d%d",&u,&v,&w);                        add(u,v,w%3);                        add(v,u,w%3);                }                min1=INF;                getroot(1,-1,n);                work(root);                _gcd=gcd(ans,n*n);                printf("%d/%d\n",ans/_gcd,n*n/_gcd);        }        return 0;}

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