HDU 1215 七夕节

http://acm.hdu.edu.cn/showproblem.php?pid=1215

类似于筛选法

#include <stdio.h>
#include <string.h>
const int N=500001;
int f[N];
int main()
{
    memset(f,0,sizeof(f));
    for (int i=1;i<N;i++)
        for (int j=i+i;j<N;j+=i) f[j]+=i;
    int T,n;
    scanf("%d",&T);
    while (T--) 
    {
        scanf("%d",&n);
        printf("%d\n",f[n]);
    }
    return 0;
}