hdu 1215 筛法

求小于n的n的因子之和

Sample Input

3
2
10
20
Sample Output

1

8

22

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<queue>
 using namespace std;
 int n,m,t;
 const int maxint=;
 int f[maxint+];
 void init()
 {
     int i,j;
     f[]=;
     for(i=;i<=maxint/;i++)        //因数
     {
         for(j=i*;j<=maxint;j+=i)
         {
             f[j]+=i;
         }
     }
 }
 int main()
 {
     int i,j,k;
     init();
     //freopen("1.in","r",stdin);
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d",&n);
         printf("%d\n",f[n]);
     }
 }