设计一个c++程序。

Question

Answer 1

代码如下：

#include <iostream>
using namespace std;

long long power(double x,int n)
{
    long long s=1;
    for(int i = 1;i<=n;i++)
        s*=x;
    return s;
}


long long factor(int n)
{
    int i=1;
    long long s=1;
    for(i=1;i<=n;i++)
        s*=i;
    return s;
}

int main()
{
    double x,y;
    int n =1;
    int flag = 1;
    double sum = 0;
    
    double item1 = 0,item2 =1;

    cin >> x;

    while(item2 - item1 > 0.00001)
    {
        sum += flag * item1;
        
        item1 = item2;
        item2 = power(x,2*n)/factor(2*n);
        
        flag = -flag;
        n++;
    }
    cout << sum <<endl;
    return 0;
}