WA 0pts 求调/hack，部分点 AC

#include<bits/stdc++.h>
#define maxn 100010
#define int long long
using namespace std;
int n,q,c[maxn],d[maxn],fa[maxn][20],sc[maxn][20],lg[maxn],dep[maxn],r,v;
stack<int> s1,s2;
vector<int> g[maxn];
void build(){
	for (int i=1;i<=n;i++){
		while (!s1.empty()){
			if (s1.top()<d[i]){
				g[i].push_back(s2.top()); // add edge
				s1.pop(), s2.pop();
			}
			else break;
		}
		s1.push(d[i]), s2.push(i);
	}
}
void dfs(int p,int fp){
	fa[p][0]=fp, dep[p]=dep[fp]+1;
	sc[p][0]=c[fp];
	for (int i=1;i<=lg[dep[p]];i++){
		fa[p][i]=fa[fa[p][i-1]][i-1];
		sc[p][i]=sc[fa[p][i-1]][i-1]+sc[p][i-1];
	}
	for (auto e:g[p]){
		dfs(e,p);
	}
}
int getans(int x,int wa){
	int ans=0;
	for (int i=lg[dep[x]];i>=0;i--){
		if (sc[x][i]<=wa){
			wa-=sc[x][i], x=fa[x][i];
		}
		if (wa==0) ans=x;
	}
	if (ans==0) ans=fa[x][0];
	return ans==n?0:ans;
}
signed main(){
	ios::sync_with_stdio(0);
	cin>>n>>q;
	for (int i=1;i<=n;i++){
		cin>>d[i]>>c[i];
	}
	for (int i=1;i<=n+4;i++){
		lg[i]=lg[i-1]+(1<<lg[i-1]==i);
	}
	d[++n]=2e18, c[n]=2e18;
	build();
	dfs(n,0);
	while (q--){
		cin>>r>>v;
		if (c[r]>=v){
			cout<<r<<"\n";
			continue;
		}
		cout<<getans(r,v-c[r])<<"\n";
	}
	return 0;
}