1787: [Ahoi2008]Meet 緊急集合

1787: [Ahoi2008]Meet 緊急集合

Time Limit: 20 Sec  Memory Limit: 162 MB
Submit: 3217  Solved: 1445
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Description

Input

Output

Sample Input

6 4
1 2
2 3
2 4
4 5
5 6
4 5 6
6 3 1
2 4 4
6 6 6

Sample Output

5 2
2 5
4 1
6 0

HINT

題解：同樣模板啊，沒什麼好講的，直接上代碼。

代碼：

#include<bits/stdc++.h>
using namespace std;
int n,q,cnt;
int deep[500001],head[500001],fa[500001][20];
bool vis[500001];
struct node
{
    int to,next;
}edge[1000001];
int read()
{
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
void ins(int u,int v)
{
    edge[++cnt].to=v;
    edge[cnt].next=head[u];
    head[u]=cnt;
}
void dfs(int x)
{
    vis[x]=1;
    for(int i=1;i<=18;i++)
    {
        if(deep[x]<(1<<i))break;
        fa[x][i]=fa[fa[x][i-1]][i-1];
    }
    for(int i=head[x];i;i=edge[i].next)
    {
        if(vis[edge[i].to])continue;
        deep[edge[i].to]=deep[x]+1;
        fa[edge[i].to][0]=x;
        dfs(edge[i].to);
    }
}
int lca(int x,int y)
{
    if(deep[x]<deep[y])swap(x,y);
    int d=deep[x]-deep[y];
    for(int i=0;i<=18;i++)
        if((1<<i)&d)x=fa[x][i];
    for(int i=18;i>=0;i--)
        if(fa[x][i]!=fa[y][i]) 
            x=fa[x][i],y=fa[y][i];
    if(x==y)return x;
    else return fa[x][0];
}
int dis(int x,int y)
{
    return deep[x]+deep[y]-2*deep[lca(x,y)];
}
int cal(int x,int y,int z)
{
    int p1=lca(x,y),p2=lca(x,z),p3=lca(y,z),t;
    if(p1==p2)t=p3;
    else
        if(p2==p3)t=p1;
        else t=p2;
    int ans;
    ans=dis(x,t)+dis(y,t)+dis(z,t);
    printf("%d %d\n",t,ans);
}
int main()
{
    n=read();q=read();
    for(int u,v,i=1;i<n;i++)
    {
        u=read();v=read();
        ins(u,v),ins(v,u);
    }
    dfs(1);
    for(int i=1,x,y,z;i<=q;i++)
        x=read(),y=read(),z=read(),cal(x,y,z);
    return 0;
}