Check whether a given number is an ugly number or not

Given an integer N, the task is to find out whether the given number is an Ugly number or not . 

Ugly numbers are numbers whose only prime factors are 2, 3 or 5.

Examples:

Input: N = 14 
Output: No 
Explanation:
14 is not ugly since it includes another prime factor 7.

Input: N = 6 
Output: Yes 
Explanation:
6 is a ugly since it includes 2 and 3. 

Approach: The idea is to use recursion to solve this problem and check if a number is divisible by 2,  3 or 5. If yes then divide the number by that and recursively check that a number is an ugly number or not. If at any time, there is no such divisor, then return false, else true.

Below is the implementation of the above approach:

C++

// C++ implementation to check if a number is an ugly number
// or not

#include <bits/stdc++.h>
using namespace std;

// Function to check if a number is an ugly number or not
int isUgly(int n)
{
    // Base Cases
    if (n == 1)
        return 1;
    if (n <= 0)
        return 0;

    // Condition to check if the number is divided by 2, 3,
    // or 5
    if (n % 2 == 0)
        return isUgly(n / 2);
    if (n % 3 == 0)
        return isUgly(n / 3);
    if (n % 5 == 0)
        return isUgly(n / 5);

    // Otherwise return false
    return 0;
}
// Driver Code
int main()
{
    int no = isUgly(14);
    if (no == 1)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
    return 0;
}

// This code is contributed by Sania Kumari Gupta (kriSania804)

C

// C implementation to check if a number is an ugly number
// or not

#include <stdio.h>

// Function to check if a number is an ugly number or not
int isUgly(int n)
{
    // Base Cases
    if (n == 1)
        return 1;
    if (n <= 0)
        return 0;

    // Condition to check if the number is divided by 2, 3,
    // or 5
    if (n % 2 == 0)
        return isUgly(n / 2);
    if (n % 3 == 0)
        return isUgly(n / 3);
    if (n % 5 == 0)
        return isUgly(n / 5);

    // Otherwise return false
    return 0;
}
// Driver Code
int main()
{
    int no = isUgly(14);
    if (no == 1)
        printf("Yes");
    else
        printf("No");
    return 0;
}

// This code is contributed by Sania Kumari Gupta (kriSania804)

Java

// Java implementation to
// check if a number is ugly number
import java.io.*;
public class GFG {

    // Function to check the ugly
    // number
    static int isUgly(int n)
    {
        // Base Cases
        if (n == 1)
            return 1;
        if (n <= 0)
            return 0;

        // Condition to check if
        // a number is divide by
        // 2, 3, or 5
        if (n % 2 == 0) {
            return (isUgly(n / 2));
        }
        if (n % 3 == 0) {
            return (isUgly(n / 3));
        }
        if (n % 5 == 0) {
            return (isUgly(n / 5));
        }
        return 0;
    }

    // Driver Code
    public static void main(String args[])
    {
        int no = isUgly(14);
        if (no == 1)
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}

Python3

# Python3 implementation to check
# if a number is an ugly number
# or not

# Function to check if a number
# is an ugly number or not
def isUgly(n):

    # Base Cases
    if (n == 1):
        return 1
    if (n <= 0):
        return 0

    # Condition to check if the
    # number is divided by 2, 3, or 5
    if (n % 2 == 0):
        return (isUgly(n // 2))

    if (n % 3 == 0):
        return (isUgly(n // 3))

    if (n % 5 == 0):
        return (isUgly(n // 5))

    # Otherwise return false
    return 0

# Driver Code
if __name__ == "__main__":

    no = isUgly(14)

    if (no == 1):
        print("Yes")
    else:
        print("No")

# This code is contributed by chitranayal

C#

// C# implementation to check
// if a number is ugly number
using System;

class GFG{

// Function to check the ugly
// number
static int isUgly(int n)
{

    // Base Cases
    if (n == 1)
        return 1;
    if (n <= 0)
        return 0;

    // Condition to check if
    // a number is divide by
    // 2, 3, or 5
    if (n % 2 == 0)
    {
        return (isUgly(n / 2));
    }
    if (n % 3 == 0)
    {
        return (isUgly(n / 3));
    }
    if (n % 5 == 0)
    {
        return (isUgly(n / 5));
    }
    return 0;
}

// Driver Code
public static void Main(String []args)
{
    int no = isUgly(14);

    if (no == 1)
        Console.WriteLine("Yes");
    else
        Console.WriteLine("No");
}
}

// This code is contributed by amal kumar choubey

Javascript

<script>

// Javascript implementation to check
// if a number is an ugly
// number or not

// Function to check if a number
// is an ugly number or not
function isUgly(n)
{
    // Base Cases
    if (n == 1)
        return 1;
    if (n <= 0)
        return 0;

    // Condition to check if the
    // number is divided by 2, 3, or 5
    if (n % 2 == 0) {
        return (isUgly(n / 2));
    }
    if (n % 3 == 0) {
        return (isUgly(n / 3));
    }
    if (n % 5 == 0) {
        return (isUgly(n / 5));
    }

    // Otherwise return false
    return 0;
}
// Driver Code

    let no = isUgly(14);
    if (no == 1)
        document.write("Yes");
    else
        document.write("No");


// This code is contributed by Mayank Tyagi

</script>

Output:

No

Time Complexity: O(log(n))
Auxiliary Space: O(1) 

METHOD 2:Using re module.

APPROACH:

The given program checks whether the given number is an ugly number or not. An ugly number is a positive number whose prime factors are only 2, 3, or 5.

ALGORITHM:

1.First, the input number is checked if it is less than or equal to 0, which is not a positive number. If the number is less than or equal to 0, the function returns False.
2.The re.findall() function is used to extract all the occurrences of ‘2’, ‘3’, or ‘5’ digits from the input number’s string representation.
3.The extracted factors are stored in a set to remove any duplicates.
4.The length of the set of extracted factors is compared with the length of the string representation of the input number to check if all the digits are prime factors of 2, 3, or 5.
5.Finally, using the all() function with a lambda function, we check if all the extracted factors are either ‘2’, ‘3’, or ‘5’.
6.If the given number is an ugly number, then the program returns True, and “Yes” is printed. Otherwise, it returns False, and “No” is printed.

Python3

import re

def is_ugly(n):
    if n <= 0:
        return False
    factors = set(re.findall('2|3|5', str(n)))
    return len(factors) == len(str(n)) and all(map(lambda x: x in ['2', '3', '5'], factors))

n = 14
if is_ugly(n):
    print("Yes")
else:
    print("No")

Output

No

Time Complexity:
The re.findall() function takes linear time proportional to the length of the string representation of the input number. Thus, the time complexity of the program is O(n), where n is the number of digits in the input number.

Auxiliary Space:
The space complexity of the program is O(n) as we are storing the extracted prime factors in a set, which can take up to n space if all the digits in the input number are prime factors of 2, 3, or 5.