Python program to print all Strong numbers in given list

Last Updated : 25 Jun, 2019

Given a list, write a Python program to print all the strong numbers in that list.

Strong Numbers are the numbers whose sum of factorial of digits is equal to the original number.

Example for checking if number is Strong Number or not.

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

Steps for checking number is strong or not :

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.

Let’s see the Python program for this problem :

# Python3 program to print 
# all strong numbers in a list. 
  
# Define a function for calculating
# factorial of a number
def factorial(number):
  
    fact = 1
      
    if number == 0 or number == 1 :
        return fact
      
    for i in range(2, number + 1) :
        fact *= i
      
    return fact
          
# Define a function for checking a 
# number is strong number or not
def find_strong_numbers(num_list):
    result = []
      
    # loop till list is not empty
    for num in num_list :
        sum = 0
        temp = num
          
        # loop till number is not zero
        while num != 0 :
              
            r = num % 10
              
            # function call
            sum += factorial(r)
              
            num //= 10
          
        # check number is strong or not
        if sum == temp:
              
            # adding number to the list
            result.append(temp)
           
    # return list of strong numbers   
    return result
              
  
# Driver Code
if __name__ == "__main__" :
      
    num_list = [145, 375, 100, 2, 10, 40585, 0]
      
    # function call
    strong_num_list = find_strong_numbers(num_list)
      
    # loop till list is not empty
    for strong_num in strong_num_list :
        print(strong_num, end =" ")
        

Output:

145 2 40585 0

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes

Related Articles