阶乘、斐波那契等递归实现

常见递归方法的实现，注意终结条件和递归过程即可。

  #include <stdio.h>

#include <tchar.h>
#include <cstdlib>
#include <iostream>
#include <sys/timeb.h>
#include <ctime>
#include <climits>
#include <cassert>
#include <cmath>

using namespace std;

//递归求和
int sum(int *arr , int len)
{
    if(len == 1)
    {
        return arr[0];
    }
    else
    {
        return arr[len-1] + sum(arr,len-1);
    }
}

//递归求阶乘
int factorial(int n)
{
    if(n == 0)
    {
        return 1;
    }
    else
    {
        return n*factorial(n-1);
    }
}

//递归求斐波那契
int fibonacci(int n)
{
    if( n <=2 )
    {
        return 1;
    }
    else
    {
        return fibonacci(n - 1) + fibonacci(n - 2);
    }
}


int _tmain(int argc, _TCHAR* argv[])
{   
    int n = 0;
    cout << "请输入数组的大小:" ;
    cin >> n;
    int *arr = new int[n];
    for(int i=0;i<n;++i)
    {
        arr[i] = rand() % 100;
    }

    cout << "该数组随机产生的数值为:" ;

    for(int i=0;i<n;++i)
    {
        cout << arr[i] << " "; 
    }

    cout << endl << "该数组的和为:" << sum(arr,n) << endl;

    for(int i=0;i<10;++i)
    {
        cout << "factorial(" << i <<") = " << factorial(i) << endl;
    }

    for(int i=0;i<10;++i)
    {
        cout << "fibonacci(" << i <<") = " << fibonacci(i) << endl;
    }

    system("pause");
    return 0;
}