View Code of Problem 71

#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<vector>
using namespace std;

float count(int n) {
	float res = 0;
	float a = 0;
	float b = 1;
	for (int i = 0; i < n; i++) {
		res = a + b;
		a = b;
		b = res;
	}
	return res;
}
int main()
{
	int n;
	float num;
	float sum = 0;
	cin >> n;
	for (int i = 1; i < n+1; i++) {
		num = count(i + 1) / count(i);
		sum = sum + num;
	}
	printf("%.2f", sum);
	cin >> sum;
	return 0;
}