Bzoj 1589: [usaco DEC] trick or treat on the farm

Description

Every Halloween, cows in Wisconsin have to dress up and wander out in the farm's n (1 ≤ n ≤ 100000) sheds to collect candy. every time they walk to an unapproved cowshed, they will collect a candy in the shed. john tried his best to make the cows happy. he set up a "next-generation cowshed" for every cowshed ". the successor of Cowshed I is Xi. he told the cows that after they arrived at a cowshed, they could collect a lot of sweets as long as they followed the cowshed. in fact, this is a bit of a deception to save his candy. the I-th cow started her journey from the cowshed. calculate how much candy each cow can collect. input

Input N in the second row, and an integer in the second row indicates the successor bucket XI of the bucket I, n rows in total. Output

There are n rows in total. An integer in one row indicates the number of Sweets that a cow can collect.

Question:

It is a base ring tree forest. You can use the base ring tree method.

You can also make sure that China Unicom's components are messy.

Code:

#include<cstdio>#include<cstring>#include<algorithm>//by zrt//problem:using namespace std;int H[100005],X[100005],P[100005];int tot;inline void add(int x,int y){    P[++tot]=y;X[tot]=H[x];H[x]=tot;}long long ans[100005];int low[100005];int stk[100005];bool instk[100005];int to[100005];int belong[100005];int hav[100005];int cnt,tim;int top;void tarjan(int x){    int dfn=low[x]=++tim;    stk[top++]=x;instk[x]=1;    if(!low[to[x]]){        tarjan(to[x]);        low[x]=min(low[x],low[to[x]]);    }else if(instk[to[x]]) low[x]=min(low[x],low[to[x]]);    if(dfn==low[x]){        int k;        cnt++;        do{            k=stk[--top];            instk[k]=0;            belong[k]=cnt;            hav[cnt]++;        }while(x!=k);    }}int ask(int x){    if(ans[x]) return ans[x];    ans[x]=hav[x];    if(hav[x]==1)        ans[x]+=ask(P[H[x]]);    return ans[x];}int main(){    #ifdef LOCAL    freopen("in.txt","r",stdin);    freopen("out.txt","w",stdout);    #endif    int n;    scanf("%d",&n);    for(int i=1;i<=n;i++){        scanf("%d",&to[i]);    }    for(int i=1;i<=n;i++){        if(!low[i]) tarjan(i);    }    for(int i=1;i<=n;i++){        if(belong[i]!=belong[to[i]]) add(belong[i],belong[to[i]]);    }    for(int i=1;i<=n;i++){        printf("%d\n",ask(belong[i]));    }    return 0;}

Bzoj 1589: [usaco DEC] trick or treat on the farm