Python Program for Find largest prime factor of a number

In this article, we will learn about the solution to the problem statement given below −

Problem statement

Given a positive integer n. We need to find the largest prime factor of a number.

Approach

• Factorise the given number input by dividing it with the divisor of a number.
• Now keep updating the maximum prime factor.

Example

 Live Demo

import math
def maxPrimeFactor(n):
   # number must be even
   while n % 2 == 0:
      max_Prime = 2
      n /= 1
   # number must be odd
   for i in range(3, int(math.sqrt(n)) + 1, 2):
      while n % i == 0:
         max_Prime = i
         n = n / i
   # prime number greator than two
   if n > 2:
      max_Prime = n
   return int(max_Prime)
# Driver code to test above function
n = 15
print(maxPrimeFactor(n))

Time complexity: O(n^½)

Auxiliary space: O(1)

Output

5

All the variables are declared in the global frame as shown in the figure given below:

Conclusion

In this article, we learnt about the approach to Find largest prime factor of a number

Pavitra

Updated on: 26-Sep-2019

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