UVa 11991 Easy Problem from Rujia Liu? (用map离散化)

/*0.099s*/

#include<bits/stdc++.h>
using namespace std;

map<int, vector<int> > a; /// 离散化，比用vector好

int main()
{
	int n, m, x, y;
	while (~scanf("%d%d", &n, &m))
	{
		a.clear();
		for (int i = 0; i < n; i++)
		{
			scanf("%d", &x);
			if (!a.count(x)) a[x] = vector<int>();
			a[x].push_back(i + 1);
		}
		while (m--)
		{
			scanf("%d%d", &x, &y);
			if (!a.count(y) || a[y].size() < x) printf("0\n");
			else printf("%d\n", a[y][x - 1]);
		}
	}
	return 0;
}