题目链接：

option=com_onlinejudge&Itemid=8&page=show_problem&problem=3142">https://uva.onlinejudge.org/index.php?

option=com_onlinejudge&Itemid=8&page=show_problem&problem=3142

题意：

给一个长度n的序列。有m询问，每一个询问会问第k个出现的数字的下标是多少

用map记录

代码：

#include <stdio.h>

#include <iostream>

#include <algorithm>

#include <string.h>

#include <queue>

#include <stack>

#include <map>

using namespace std;

int n, m;

map<int ,vector<int> > mp;

int c[1001000];

int main()

{

    while (~scanf("%d%d", &n, &m))

    {

        mp.clear();

        memset(c, 0, sizeof(c));

        int tmp;

        for (int i = 1; i <= n; i++)

        {

            scanf("%d", &tmp);

            mp[tmp].push_back(i);

        }

        int a, b;

        while (m--)

        {

            scanf("%d%d", &a, &b);

            if (mp[b].size() < a) printf("0\n");

            else printf("%d\n", mp[b][a - 1]);

        }

    }

    return 0;

}