POJ1470Closest Common Ancestors 最近公共祖先LCA 的 离线算法 Tarjan

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
const int MAXN=905;
int father[MAXN],ancestor[MAXN];
bool visit[MAXN];
int ans[MAXN];
vector<int> map[MAXN];//save the tree
vector<int> query[MAXN];//save the query
int n,t,root;
bool indegree[MAXN];//the indegree to find the root
int getfather(int v){//path compression
    if(father[v]==v)return v;
    return father[v]=getfather(father[v]);
}
void aunion(int u,int v){//??
    int fv=getfather(v),fu=getfather(u);
    father[fv]=fu;
}
void LCA(int id){
    int len=map[id].size();
    for(int i=0;i<len;i++){
        int son=map[id][i];
        LCA(son);
        aunion(id,son);
    }
    visit[id]=1;
    len=query[id].size();
    for(int i=0;i<len;i++){
        int son=query[id][i];
        if(visit[son])
            ans[father[getfather(son)]]++;
    }

}
void init(){
    int x,y,z;
    for(int i=0;i<=n;i++){
        map[i].clear();
        query[i].clear();
    }
    memset(visit,0,sizeof(visit));
    memset(ans,0,sizeof(ans));
    memset(indegree,0,sizeof(indegree));
    for(int i=0;i<=n;i++)father[i]=i;
    for(int i=0;i<n;i++){
        scanf("%d:(%d)",&x,&y);
        for(int j=0;j<y;j++){
            scanf("%d",&z);
            indegree[z]=1;
            map[x].push_back(z);
        }
    }
    scanf("%d",&t);
    while(t--){//this method of the init is really clever
        while(getchar()!='(');
        scanf("%d%d",&x,&y);
        query[x].push_back(y);
        query[y].push_back(x);
    }
    while(getchar()!=')');
    for(int i=1;i<=n;i++)if(!indegree[i])root=i;//find the root;warning:the 0
}
void output(){
    for(int i=1;i<=n;i++){
        if(ans[i]!=0)
            printf("%d:%d\n",i,ans[i]);
    }

}
int main(){
    while(scanf("%d",&n)!=EOF){
        init();
        LCA(root);
        output();
    }
    return 0;
}