Module: (Python) Subroutines: Procedures and Functions - 2


Problem

5/8

Logic functions. Perfect Numbers

Theory Click to read/hide

Logic functions

Often programmers use boolean functions that return boolean values ​​"true" or "false" (trueor false)
Such functions are useful for   check some property.
Let's consider two examples of writing a logical function that checks if a number is even.
 
Description Subroutine example
1) Better way: the result of the expression n % 2 == 0 will be true (True) or false (False) 
def isEven(n):
    return (n % 2 == 0)
2) You can write it like that, but it’s better not to do a longer record anyway 
def isEven(n):
    if n % 2 == 0:
        return true;
    else:
        return False

And the last note about working with functions and procedures: the number of functions and procedures in the program is not limited. In addition, one subroutine can call another subroutine and even itself.
 

Problem

A perfect number is a number equal to the sum of all its divisors less than itself (for example, the number 6 = 1 + 2 + 3). Write a program that inputs a natural number N and determines if the number N is perfect . Use  a function to find the sum of the divisors of a number and a logical function to check whether the number is perfect or not.
 

Input
The input string contains a natural number N .

Imprint
If the number N – perfect, the program should output the word 'YES', otherwise – the word 'NO'.

 

Examples
# Input Output
1 28 YES
2 29 NO

time 1000 ms
memory 256 Mb
Rules for program design and list of errors in automatic problem checking

Teacher commentary

Insert the missing code snippets
Python
Write the program below 
def SumOfDivisions(n):        
def isPerfectNumber(n):        
N = int(input())

     

Program check result

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