SPOJ Problem 4300:Rectangles

用给定数目的单位方块，问能拼成多少种矩形。暴力求解。。

#include<cstdio>
#include<cmath>
int n,i,j,ans;
int main(){
    scanf("%d",&n);
    for (i=1;i<=n;i++){
        for (j=1;j<=int(sqrt(double(i)));j++){
            if (i%j==0)ans++;
        }
    }
    printf("%d\n",ans);
}