树上查分模板

#include<bits/stdc++.h>
using namespace std;
const int maxn=2e5+10;
int n,m,s;
int a[maxn];
int h[maxn<<1],nxt[maxn<<1],to[maxn<<1],tot;
int Log[maxn];
int dep[maxn];
int fa[maxn][35];
int num[maxn];
int ans;
void add(int x,int y)
{tot++;to[tot]=y;nxt[tot]=h[x];h[x]=tot;
}
void llog(){for (int i=2;i<=n;i++) Log[i]=Log[i>>1]+1;}
void dfs(int now,int f)
{dep[now]=dep[f]+1;fa[now][0]=f;for (int i=1;i<=30;i++){fa[now][i]=fa[fa[now][i-1]][i-1];}for (int i=h[now];i;i=nxt[i]){int y=to[i];if (y == f) continue;dfs(y,now);}
}
int lca(int x,int y)
{if (dep[x]>dep[y]) swap(x,y);int d=dep[y]-dep[x];for (int i=Log[d];i>=0;i--){if (d>>i&1) y=fa[y][i]; }if (x == y) return x;for (int i=Log[dep[x]];i>=0;i--){if (fa[x][i]!=fa[y][i]){x=fa[x][i];y=fa[y][i];}}return fa[x][0];
}
void dfs_num(int now,int f)
{for (int i=h[now];i;i=nxt[i]){int y=to[i];if (y == f) continue;dfs_num(y,now);num[now]+=num[y];}ans=max(ans,num[now]);
}
int main()
{cin >> n >> m;llog();for (int i=1;i<=n-1;i++){int x,y;cin >> x >> y;add(x,y);add(y,x);}dfs(1,0);while(m--){int x,y;cin >> x >> y;int Lca=lca(x,y);num[x]++;num[y]++;num[Lca]--;if (Lca!=1) num[fa[Lca][0]]--;}dfs_num(1,0);cout << ans << endl;return 0;
}