POJ 1330 LCA+并查集求最近公共祖先

Problem：

http://poj.org/problem?id=1330

 

 

my code:

 

#include<stdio.h>#include<string.h>#include<vector>#include<iostream>#define MAX 10005using namespace std;vector<int> tree[MAX],Q[MAX];int father[MAX],path[MAX];bool used[MAX];int all[MAX],ans[MAX];int find(int x){if(father[x]==x)return x;elsereturn father[x]=find(father[x]);}void Union(int x,int y){int xx,yy;xx=find(x);yy=find(y);if(xx==yy)return ;if(path[xx]<=path[yy]){father[xx]=yy;path[yy]+=path[xx];}else{father[yy]=xx;path[xx]+=path[yy];}}void LCA(int x){int i;ans[x]=x;for(i=0;i<tree[x].size();i++){LCA(tree[x][i]);Union(x,tree[x][i]);ans[find(x)]=x;}used[x]=true;for(i=0;i<Q[x].size();i++){if(used[Q[x][i]]){printf("%d/n",ans[find(Q[x][i])]);}}}int main(){int t;int i;int n;int from,to;scanf("%d",&t);while(t--){scanf("%d",&n);for(i=1;i<=n;i++){father[i]=i;path[i]=1;used[i]=false;all[i]=0;ans[i]=0;tree[i].clear();Q[i].clear();}for(i=1;i<n;i++){scanf("%d%d",&from,&to);tree[from].push_back(to);all[to]++;}scanf("%d%d",&from,&to);Q[from].push_back(to);Q[to].push_back(from);for(i=1;i<=n;i++){if(all[i]==0){LCA(i);break;}}}return 0;}