最近公共祖先模版

LCA tarjan 的离线算法

#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;
const int maxn = 40010;
int first[maxn], head[maxn], cnt, sum;
struct edge
{
	int u, v, w, next;
}e[maxn*2], qe[maxn], Q[maxn];
int ans[maxn];
int f[maxn], vis[maxn];
int d[maxn];
void AddEdge(int u, int v, int w)
{
	e[cnt].u = u;
	e[cnt].v = v;
	e[cnt].w = w;
	e[cnt].next = first[u];
	first[u] = cnt++;
	e[cnt].u = v;
	e[cnt].v = u;
	e[cnt].w = w;
	e[cnt].next = first[v];
	first[v] = cnt++;
}

int find(int x)
{
	if(f[x] != x)
		return f[x] = find(f[x]);
	return f[x];
}
void LCA(int u, int k)
{
	f[u] = u;
	d[u] = k;
	vis[u] = true;
	for(int i = first[u]; i != -1; i = e[i].next)
	{
		int v = e[i].v;
		if(vis[v])
			continue;	
		LCA(v, k + e[i].w);
		f[v] = u;
	}
	for(int i = head[u]; i != -1; i = qe[i].next)
	{
		int v = qe[i].v;
		if(vis[v])
		{
			ans[qe[i].w] = find(v);
		}
	}
} 

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最近公共祖先模版

原文：http://blog.csdn.net/u011686226/article/details/37565637