UVA 11991 Easy Problem from Rujia Liu?

题目链接

#include <cstdio>
#include <map>
#include <vector>
using namespace std;
map<int,vector<int>> ma;
int main()
{
    int n,m,x,k,v,num;
    while(scanf("%d%d",&n,&m)==2){
        ma.clear();
        for(int i=1;i<=n;i++){
            scanf("%d",&x);
            ma[x].push_back(i);
        }
        for(int i=0;i<m;i++){
            scanf("%d%d",&k,&v);
            if(ma[v].size()<k) puts("0");
            else printf("%d
",ma[v][k-1]);
        }
    }
}