uva 11991 简单hash

数据最大只有100W，果断hash之。

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

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

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
", query( k, val ));
        }
    }
    return 0;
}