# 【bzoj1787】[Ahoi2008]Meet 紧急集合 倍增LCA

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#include <cstdio>
#include <algorithm>
using namespace std;
int head[500010] , to[1000010] , next[1000010] , cnt , log[500010] , fa[500010][21] , deep[500010];
void add(int x , int y)
{
}
void dfs(int x)
{
int i;
for(i = 1 ; i <= log[deep[x]] ; i ++ ) fa[x][i] = fa[fa[x][i - 1]][i - 1];
for(i = head[x] ; i ; i = next[i])
if(to[i] != fa[x][0])
fa[to[i]][0] = x , deep[to[i]] = deep[x] + 1 , dfs(to[i]);
}
int getlca(int x , int y)
{
int i;
if(deep[x] < deep[y]) swap(x , y);
for(i = log[deep[x] - deep[y]] ; ~i ; i -- )
if(deep[x] - (1 << i) >= deep[y])
x = fa[x][i];
if(x == y) return x;
for(i = log[deep[x]] ; ~i ; i -- )
if(fa[x][i] != fa[y][i])
x = fa[x][i] , y = fa[y][i];
return fa[x][0];
}
int main()
{
int n , m , i , x , y , z , xy , xz , yz , t;
scanf("%d%d" , &n , &m);
for(i = 1 ; i < n ; i ++ )
scanf("%d%d" , &x , &y) , add(x , y) , add(y , x);
for(i = 2 ; i <= n ; i ++ ) log[i] = log[i >> 1] + 1;
dfs(1);
while(m -- )
{
scanf("%d%d%d" , &x , &y , &z);
xy = getlca(x , y) , xz = getlca(x , z) , yz = getlca(y , z) , t = deep[x] + deep[y] + deep[z] - 2 * deep[getlca(xy , z)];
if(deep[xy] > deep[xz] && deep[xy] > deep[yz]) printf("%d %d\n" , xy , t - deep[xy]);
else if(deep[xz] > deep[yz]) printf("%d %d\n" , xz , t - deep[xz]);
else printf("%d %d\n" , yz , t - deep[yz]);
}
return 0;
}

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posted @ 2017-03-27 12:59  GXZlegend  阅读(185)  评论(0编辑  收藏  举报