Program to Check if the Given Number is Power of 3 (K) | Python, C/C++

Problem statement:

Write a Python, C/C++ program to check if the given number is the power of 3 (k- any other integer number).

Example:

The numbers which are the power of three: 3 (3^1), 9 (3^2), 27 (3^3), 81 (3^4), etc.
The numbers which are not the power of three: 2, 4, 5, 6, 18.

Note: Some number that is divisible by three not necessarily to be the power of three. Example: 18, 36

Program to Check if the Given Number is Power of 3 (K)

Algorithm:

1. If the n==k and k==1, given number (n) is the power of k. Return true.
2. If n is not divisible by k, given number (n) is not a power of k. Return false.
3. Repeat steps 1 and 2 where n=n/k.

Python Code

Prerequisite:

• if-el-if statement in Python

Python Program:

def isPowerOf(n, k):
  if n==k or n==1:
    return True
  n=n/k
  if not n.is_integer():
    return False
  else:
    return isPowerOf(n, k)

#check the numbers
print(isPowerOf(10, 3))
print(isPowerOf(15, 2))
print(isPowerOf(64, 4))
print(isPowerOf(27, 3))
print(isPowerOf(81, 3))

Output:

False
False
True
True
True

You can also take the ‘n’ and ‘k’ values as user input in Python.

C/C++ Code

Prerequisite:

• if-else Statement in C/C++
• Different Types of Recursion in C

C/C++ Program:

#include <stdio.h>

#define TRUE 1
#define FALSE 0

int isPowerOf(int n, int k)
{
  if(n==k || n==1)
    return(TRUE);
  if(n%k)
    return(FALSE);
  else
    return isPowerOf(n/k, k);
}

//driver function for testing
void testFunction(int n, int k)
{
  int out = isPowerOf(n, k);
  if(out)
    printf("%d is power of %d\n", n, k);
  else
    printf("%d is not power of %d\n", n, k);
}
void main()
{
  testFunction(10, 3);
  testFunction(15, 2);
  testFunction(64, 4);
  testFunction(27, 3);
  testFunction(81, 3);
}

Output:

10 is not power of 3
15 is not power of 2
64 is power of 4
27 is power of 3
81 is power of 3

This is one of the most common coding questions asked in a placement interview. Try to solve these different programming languages like Python, C/C++, Java. The logic remains the same.

Aniruddha Chaudhari

I am a Python enthusiast who loves Linux and Vim. I hold a Master of Computer Science degree from NIT Trichy and have 10 years of experience in the IT industry, focusing on the Software Development Lifecycle from Requirements Gathering, Design, Development to Deployment. I have worked at IBM, Ericsson, and NetApp, and I share my knowledge on CSEstack.org.