计算给定范围内的阶乘数

如果存在一些整数I> = 0，使得F = I，则数字F是阶乘数。 (也就是说，F是I的阶乘)。阶乘数的示例是1、2、6、24、120等。
编写一个程序，将两个长整数’low’和’high’作为输入，其中0 例子 ：

Input: 0 1 
Output: 1 //Reason: Only factorial number is 1 

Input: 12 122 
Output: 2 // Reason: factorial numbers are 24, 120 

Input: 2 720 
Output: 5 // Factorial numbers are: 2, 6, 24, 120, 720 

1)找到大于或等于低的第一个阶乘。让这个阶乘为x！ (x的阶乘)和该阶乘的值是“事实”
2)不断增加x，并在事实小于或等于high时继续更新“事实”。计算该循环运行的次数。
3)返回在步骤2中计算的计数。
下面是上述算法的实现。感谢Kartik提供以下解决方案的建议。

C++

// Program to count factorial numbers in given range
#include 
using namespace std;
 
int countFact(int low, int high)
{
    // Find the first factorial number 'fact' greater than or
    // equal to 'low'
    int fact = 1, x = 1;
    while (fact < low)
    {
        fact = fact*x;
        x++;
    }
 
    // Count factorial numbers in range [low, high]
    int res = 0;
    while (fact <= high)
    {
        res++;
        fact = fact*x;
        x++;
    }
 
    // Return the count
    return res;
}
 
// Driver program to test above function
int main()
{
    cout << "Count is " << countFact(2, 720);
    return 0;
}

Java

// Java Program to count factorial
// numbers in given range
 
class GFG
{
    static int countFact(int low, int high)
    {
        // Find the first factorial number
        // 'fact' greater than or equal to 'low'
        int fact = 1, x = 1;
        while (fact < low)
        {
            fact = fact * x;
            x++;
        }
     
        // Count factorial numbers
        // in range [low, high]
        int res = 0;
        while (fact <= high)
        {
            res++;
            fact = fact * x;
            x++;
        }
     
        // Return the count
        return res;
    }
     
    // Driver code
    public static void main (String[] args)
    {
        System.out.print("Count is "
                         + countFact(2, 720));
    }
}
 
// This code is contributed by Anant Agarwal.

Python3

# Program to count factorial
# numbers in given range
 
def countFact(low,high):
 
    # Find the first factorial number
    # 'fact' greater than or
    # equal to 'low'
    fact = 1
    x = 1
    while (fact < low):
     
        fact = fact * x
        x += 1
     
  
    # Count factorial numbers
    # in range [low, high]
    res = 0
    while (fact <= high):
     
        res += 1
        fact = fact * x
        x += 1
     
  
    # Return the count
    return res
 
# Driver code
 
print("Count is ", countFact(2, 720))
 
# This code is contributed
# by Anant Agarwal.

C#

// C# Program to count factorial
// numbers in given range
using System;
 
public class GFG
{
     
    // Function to count factorial
    static int countFact(int low, int high)
    {
         
        // Find the first factorial number numbers
        // 'fact' greater than or equal to 'low'
        int fact = 1, x = 1;
        while (fact < low)
        {
            fact = fact * x;
            x++;
        }
     
        // Count factorial numbers
        // in range [low, high]
        int res = 0;
        while (fact <= high)
        {
            res++;
            fact = fact * x;
            x++;
        }
     
        // Return the count
        return res;
    }
     
    // Driver code
    public static void Main ()
    {
        Console.Write("Count is " + countFact(2, 720));
    }
}
 
// This code is contributed by Sam007

Javascript

// Javascript Program to count factorial
// numbers in given range
function countFact(low, high)
{
 
    // Find the first factorial
    // number 'fact' greater
    // than or equal to 'low'
    let fact = 1;
    let x = 1;
    while (fact < low)
    {
        fact = fact * x;
        x++;
    }
 
    // Count factorial numbers
    // in range [low, high]
    let res = 0;
    while (fact <= high)
    {
        res++;
        fact = fact * x;
        x++;
    }
 
    // Return the count
    return res;
}
 
// Driver Code
document.write("Count is " + countFact(2, 720));
 
// This code is contributed by _saurabh_jaiswal

输出 ：

Count is 5