訓練指南-3.1數據結構-uva11991(map)

#include<cstdio>
#include<iostream>
#include<map>
#include<vector>
using namespace std;
map<int,vector<int> > a;
int main(){
	int n,m,x,y;
	while(cin>>n>>m){
		a.clear();//
		for(int i=0;i<n;i++){
			cin>>x;
			if(!a.count(x)) a[x]=vector<int>();//
			a[x].push_back(i+1);
		}
		while(m--){
			cin>>x>>y;
			if(!a.count(y)||a[y].size()<x) cout<<"0\n";
			else cout<<a[y][x-1]<<endl;
		}
	}
	return 0;
}