程序检查强数

强数是数字的阶乘之和等于原始数字的数字。给定一个数字，检查它是否为强数。
例子：

Input  : n = 145
Output : Yes
Sum of digit factorials = 1! + 4! + 5!
                        = 1 + 24 + 120
                        = 145

Input :  n = 534
Output : No

1) Initialize sum of factorials as 0. 
2) For every digit d, do following
   a) Add d! to sum of factorials.
3) If sum factorials is same as given 
   number, return true.
4) Else return false.

一种优化是预先计算从0到10的所有数字的阶乘。

C++

// C++ program to check if a number is
// strong or not.
#include 
using namespace std;
 
int f[10];
 
// Fills factorials of digits from 0 to 9.
void preCompute()
{
    f[0] = f[1] = 1;
    for (int i = 2; i<10; ++i)
        f[i] = f[i-1] * i;
}
 
// Returns true if x is Strong
bool isStrong(int x)
{
    int factSum = 0;
 
    // Traverse through all digits of x.
    int temp = x;
    while (temp)
    {
        factSum += f[temp%10];
        temp /= 10;
    }
 
    return (factSum == x);
}
 
// Driver code
int main()
{
    preCompute();
 
    int x = 145;
    isStrong(x) ? cout << "Yes\n" : cout << "No\n";
    x = 534;
    isStrong(x) ? cout << "Yes\n" : cout << "No\n";
    return 0;
}

Java

// Java program to check if
// a number is Strong or not
 
class CheckStrong
{
    static int f[] = new int[10];
  
    // Fills factorials of digits from 0 to 9.
    static void preCompute()
    {
        f[0] = f[1] = 1;
        for (int i = 2; i<10; ++i)
            f[i] = f[i-1] * i;
    }
     
    // Returns true if x is Strong
    static boolean isStrong(int x)
    {
        int factSum = 0;
      
        // Traverse through all digits of x.
        int temp = x;
        while (temp>0)
        {
            factSum += f[temp%10];
            temp /= 10;
        }
      
        return (factSum == x);
    }
     
    // main function
    public static void main (String[] args)
    {  
        // calling preCompute
        preCompute();
     
        // first pass
        int x = 145;
        if(isStrong(x))
        {
            System.out.println("Yes");
        }
        else
            System.out.println("No");
             
        // second pass
        x = 534;
        if(isStrong(x))
        {
            System.out.println("Yes");
        }
        else
            System.out.println("No");
    }
}

Python

# Python program to check if a number is
# strong or not.
 
f = [None] * 10
 
# Fills factorials of digits from 0 to 9.
def preCompute() :
    f[0] = f[1] = 1;
    for i in range(2,10) :
        f[i] = f[i-1] * i
  
# Returns true if x is Strong
def isStrong(x) :
     
    factSum = 0
    # Traverse through all digits of x.
    temp = x
    while (temp) :
        factSum = factSum + f[temp % 10]
        temp = temp / 10
 
    return (factSum == x)
     
# Driver code
preCompute()
x = 145
if(isStrong(x) ) :
    print "Yes"
else :
    print "No"
x = 534
if(isStrong(x)) :
    print "Yes"
else:
    print "No"
 
# This code is contributed by Nikita Tiwari.

C#

// C# program to check if
// a number is Strong or not
using System;
 
class CheckStrong
{
    static int []f = new int[10];
 
    // Fills factorials of digits from 0 to 9.
    static void preCompute()
    {
        f[0] = f[1] = 1;
        for (int i = 2; i < 10; ++i)
            f[i] = f[i - 1] * i;
    }
     
    // Returns true if x is Strong
    static bool isStrong(int x)
    {
        int factSum = 0;
     
        // Traverse through all digits of x.
        int temp = x;
        while (temp > 0)
        {
            factSum += f[temp % 10];
            temp /= 10;
        }
     
        return (factSum == x);
    }
     
    // Driver Code
    public static void Main ()
    {
        // calling preCompute
        preCompute();
     
        // first pass
        int x = 145;
        if(isStrong(x))
        {
            Console.WriteLine("Yes");
        }
        else
            Console.WriteLine("No");
             
        // second pass
        x = 534;
        if(isStrong(x))
        {
            Console.WriteLine("Yes");
        }
        else
            Console.WriteLine("No");
    }
}
 
// This code is contributed by Nitin Mittal.

Javascript

 
// Javascript program to check if a number is
// strong or not.
 
 
let f = new Array(10);
 
// Fills factorials of digits from 0 to 9.
function preCompute()
{
    f[0] = f[1] = 1;
    for (let i = 2; i<10; ++i)
        f[i] = f[i-1] * i;
}
 
// Returns true if x is Strong
function isStrong(x)
{
    let factSum = 0;
 
    // Traverse through all digits of x.
    let temp = x;
    while (temp)
    {
        factSum += f[temp%10];
        temp = Math.floor(temp/10);
    }
 
    return (factSum == x);
}
 
// Driver code
 
    preCompute();
 
    let x = 145;
    isStrong(x) ? document.write("Yes" + "<br>") :
    document.write("No" + "<br>");
    x = 534;
    isStrong(x) ? document.write("Yes" + "<br>") :
    document.write("No" + "<br>");
 
 
//This code is contributed by Mayank Tyagi
 

输出：

Yes
No