Program to check for Peterson number - GeeksforGeeks

31 Aug, 2021
A number is said to be a Peterson number if the sum of factorials of each digit of the number is equal to the number itself.
Example: 
Input : n = 145
Output = Yes
Explanation:
 145 = 5! + 4! + 1!
     = 120 + 24 +1
     = 145

Input  : n = 55
Output : No
Explanation: 5! + 5!
            = 120 + 120
            = 240
Since 55 is not equal to 240
It is not a Peterson number.     
We will pick each digit (Starting from the last digit) of the given number and find its factorial. And add all factorials. Finally, we check if the sum of factorials is equal to number or not. 
C++
Java
Python3
C#
PHP
Javascript
// C++ program to determine whether the number is// Peterson number or not#include <iostream>using namespace std; // To quickly find factorial of digitsint fact[10]    = { 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880 }; // Function to check if a number is Peterson// or notbool peterson(int n){    int num = n, sum = 0;     // stores the sum of factorials of    // each digit of the number.    while (n > 0) {        int digit = n % 10;        sum += fact[digit];        n = n / 10;    }     // Condition check for a number to    // be a Peterson Number    return (sum == num);} // Driver Programint main(){    int n = 145;    if (peterson(n))        cout << "Yes";    else        cout << "No";    return 0;}
//checks whether a number entered by user is peterson number or notimport java.util.*;class GFG{    public static void main(String args[])    {        Scanner sc=new Scanner(System.in);      //taking input from the user      System.out.println("Enter the number");        int num=sc.nextInt();        int temp=num;//storing the number in a temporary variable        int f=1,sum=0;        while(num!=0)//running while loop until number becomes zero        {            f=1;          //extracting last digit of the number          //and storing in r            int r=num%10;          //for loop to find the factorial of a digit            for(int i=1;i<=r;i++)            {                f=f*i;            }            sum=sum+f;//adding the factotial of the digits            num=num/10;        }      //checking if the sum of the factorial of digits      //is equal to the number or not        if(sum==temp)        System.out.println("PETERSON NUMBER");        else        System.out.println("NOT PETERSON NUMBER");    }    }
# Python3 code to determine whether the# number is Peterson number or not # To quickly find factorial of digitsfact = [1, 1, 2, 6, 24, 120, 720,        5040, 40320, 362880] # Function to check if a number# is Peterson or not  def peterson(n):    num = n    sum = 0     # stores the sum of factorials of    # each digit of the number.    while n > 0:        digit = int(n % 10)        sum += fact[digit]        n = int(n / 10)     # Condition check for a number    # to be a Peterson Number    return (sum == num)  # Driver Coden = 145print("Yes" if peterson(n) else "No") # This code is contributed by "Sharad_Bhardwaj"..
// C# program to determine whether the// number is Peterson number or notusing System; public class GFG {     // To quickly find factorial of digits    static int[] fact        = new int[10] { 1,   1,   2,    6,     24,                        120, 720, 5040, 40320, 362880 };     // Function to check if a number is    // Peterson or not    static bool peterson(int n)    {        int num = n;        int sum = 0;         // stores the sum of factorials of        // each digit of the number.        while (n > 0) {            int digit = n % 10;            sum += fact[digit];            n = n / 10;        }         // Condition check for a number to        // be a Peterson Number        return (sum == num);    }     // Driver Program    static public void Main()    {        int n = 145;         if (peterson(n))            Console.WriteLine("Yes");        else            Console.WriteLine("No");    }} // This code is contributed by vt_m.
<?php// PHP program to determine// whether the number is// Peterson number or not // To quickly find// factorial of digits$fact =array (1, 1, 2, 6, 24, 120, 720,                  5040, 40320, 362880); // Function to check if// a number is Peterson// or notfunction peterson($n){    $num = $n; $sum = 0;     // stores the sum of factorials of    // each digit of the number.    while ($n > 0)    {        $digit = $n % 10;        $n = $n / 10;        }     // Condition check for    // a number to be a    // Peterson Number    return ($sum == $num);}     // Driver Code    $n = 145;    if (peterson($n))        echo "Yes";    else        echo"No";     // This code is contributed by ajit?>
<script> // Javascript program to determine whether// the number is Peterson number or not // To quickly find factorial of digitslet fact = [ 1, 1, 2, 6, 24, 120,             720, 5040, 40320, 362880 ]; // Function to check if a number is// Peterson or notfunction peterson(n){    let num = n, sum = 0;     // stores the sum of factorials of    // each digit of the number.    while (n > 0)    {        let digit = n % 10;        sum += fact[digit];        n = parseInt(n / 10);    }     // Condition check for a number to    // be a Peterson Number    return (sum == num);} // Driver codelet n = 145;if (peterson(n))    document.write("Yes");else    document.write("No");     // This code is contributed by souravmahato348 </script>
Output: 
 
vt_m
jit_t
rayvantsahni
souravmahato348
abhishekinvestment0209
factorial
number-digits
School Programming
factorial
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