uva 11991 简单hash

#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
using namespace std;

const int N = 1000001;
vector<int> v
;

void init()
{
for ( int i = 0; i < N; i++ )
{
v[i].clear();
}
}

int query( int k, int val )
{
if ( v[val].size() < k ) return 0;
return v[val][k - 1];
}

int main ()
{
int n, m;
while ( scanf("%d%d", &n, &m) != EOF )
{
init();
for ( int i = 1; i <= n; i++ )
{
int tmp;
scanf("%d", &tmp);
v[tmp].push_back(i);
}
while ( m-- )
{
int k, val;
scanf("%d%d", &k, &val);
printf("%d\n", query( k, val ));
}
}
return 0;
}