多好的莫队啊

不用可惜了

#include<bits/stdc++.h>
#define int long long
using namespace std;
int c[200005];
vector<int> ve[200005];
int n,q,in[200005],out[200005],posc[200005],ts,fr[200005],cn[200005];
bool vis[200005];
struct node{
    int l,r,t,idx;
}qry[200005];
int bs,ans[200005];   
bool cmp(node a,node b){
    if(a.l / bs != b.l / bs) return a.l < b.l;
    return (a.l / bs % 2) ? (a.r > b.r) : (a.r < b.r);
}
stack<pair<int,int>> st;
void dfs(int rt){
    st.push({rt,-1});
    ts = 0;
    memset(vis,0,sizeof vis);
    while(!st.empty()){
        auto [u,p] = st.top();
        if(!vis[u]){
            vis[u] = 1;
            in[u] = ++ts;
            posc[ts] = c[u];
            for(auto v : ve[u]){
                if(v != p) st.push({v,u});
            }
        }else{
            out[u] = ts;
            st.pop();
        }
    }
}
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> q;
    for(int i = 1;i <= n;i++) cin >> c[i];
    for(int i = 1;i < n;i++){
        int u,v; cin >> u >> v;
        ve[u].push_back(v);
        ve[v].push_back(u);
    }
    dfs(1);
    for(int i = 1;i <= q;i++){
        int u, t;
        cin >> u >> t;
        qry[i] = {in[u],out[u],t,i};
    }
    bs = sqrt(n) + 1;
    sort(qry + 1,qry + q + 1,cmp);
    int cl = 1,cr = 0;
    for(int i = 1;i <= q;i++){
        int l = qry[i].l,r = qry[i].r;
        int t = qry[i].t,idx = qry[i].idx;
        while(cl > l){
            cl--;
            int x = posc[cl];
            int of = fr[x];
            fr[x]++;
            cn[of + 1]++;
        }
        while(cr < r){
            cr++;
            int x = posc[cr];
            int of = fr[x];
            fr[x]++;
            cn[of + 1]++;
        }
        while(cl < l){
            int x = posc[cl];
            int of = fr[x];
            cn[fr[x]]--;
            fr[x]--;
            cl++;
        }
        while(cr > r){
            int x = posc[cr];
            int of = fr[x];
            cn[of]--;
            fr[x]--;
            cr--;
        }
        ans[idx] = (t > (r - l + 1)) ? 0 : cn[t];
    }
    for(int i = 1;i <= q;i++) cout << ans[i] << "\n";
    return 0;
}