最近公用祖先模版

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LCA tarjan 的離線演算法

#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);}}}