hdu 5211 类似筛法的思想

暴力好像也可以过，不过正解应该是用类似筛法的思想来做。

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

const int INF = 9999999;
const int N = 10001;
int a[N];
int mp[N];

int main()
{
    int n;
    while ( scanf("%d", &n) != EOF )
    {
        memset( mp, -1, sizeof(mp) );
        int maxn = -1;
        for ( int i = 1; i <= n; i++ )
        {
            scanf("%d", a + i);
            if ( a[i] > maxn ) maxn = a[i];
            mp[a[i]] = i;
        }
        int ans = 0;
        for ( int i = 1; i <= n; i++ )
        {
            int f = INF;
            for ( int j = a[i] + a[i]; j <= maxn; j += a[i] )
            {
                if ( mp[j] > i )
                {
                    if ( mp[j] < f ) f = mp[j];
                }
            }
            if ( f == INF ) f = 0;
            ans += f;
        }
        printf("%d
", ans);
    }
    return 0;
}