(C Language Network) Topic 1018: Summing Regular Sequences

 

#include<iostream>
using namespace std;
int main()
{
    int N;
    cin >> N;
    double sum = 0,num ;//num用来记录更新的分母
    int count = 0;
    int i = 1,j = 2,k;//K用来保存分子 
	for( ;count < N ;)
	{
		num = j*1.0 / i;
		k = j;
		sum += num;
		count ++;
		j += i; 
		i = k;
	 } 
	 printf("%.2f",sum);
    return 0;
}