AIZU Lowest Common Ancestor Tarjan求LCA

来源：互联网发布：nginx ip hash 编辑：程序博客网时间：2024/06/16 14:22

今天刚刚会写Tarjan离线LCA…(捂脸…)

代码如下：

#include<algorithm>#include<iostream>#include<cstring>#include<cstdio>#include<vector>//by NeighThornusing namespace std;const int maxn=100000+5;int n,q,hd[maxn],to[maxn*2],nxt[maxn*2],cnt,vis[maxn],fa[maxn],ans[maxn];struct M{    int y,id;    M(int a=0,int b=0){        y=a,id=b;    }};vector<M> v[maxn];inline int find(int x){    return fa[x]==x?x:fa[x]=find(fa[x]);    }inline void add(int x,int y){    to[cnt]=y;nxt[cnt]=hd[x];hd[x]=cnt++;   }inline void tarjan(int root){    vis[root]=1;    for(int i=0;i<(int)v[root].size();i++)        if(vis[v[root][i].y])            ans[v[root][i].id]=find(v[root][i].y);    for(int i=hd[root];i!=-1;i=nxt[i])        if(!vis[to[i]])            tarjan(to[i]),fa[to[i]]=root;}signed main(void){    scanf("%d",&n);cnt=0;    memset(hd,-1,sizeof(hd));    for(int i=0,k;i<n;i++){        scanf("%d",&k);        for(int j=1,x;j<=k;j++)            scanf("%d",&x),add(i,x),add(x,i);    }scanf("%d",&q);    for(int i=0;i<n;i++)        fa[i]=i,vis[i]=0;    for(int i=1,x,y;i<=q;i++)        scanf("%d%d",&x,&y),v[x].push_back(M(y,i)),v[y].push_back(M(x,i));    tarjan(0);    for(int i=1;i<=q;i++)        printf("%d\n",ans[i]);    return 0;   }

by >_< NeighThorn

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