求平方根序列前N项和

Question

Answer 1

#include <stdio.h>
#include <math.h>
int main()
{
    int i,N;
    double sum = 0;
    scanf("%d",&N);
    for(i=1;i<=N;i++)
        sum += sqrt((double)i);
    printf("%.2lf",sum);
    return 0;
}