Python program to Find the Jumbo GCD subarray

Namachila October 29, 2025

0 1 1 minute read

Given an array, write a program to find the maximum GCD among all the subarray of the size >= 2 of the given array.

Examples:

Input list: [2, 3, 4, 4, 4]
Output: 4

Input list: [3, 7, 2, 9, 18, 5, 1, 13 ]
Output: 9

Approach:

Import the math module for python
Introduce a variable(say, V1) to store the gcd of each element of the list while looping through the list.
Iterate through the elements of the array or list using a loop.
At each iteration call the math.gcd() function.
Store the outcome of the math.gcd() function to another variable (say, V2) at each iteration.
Now compare V1 and V2. If V2 is greater than V1, set V1 equal to V2 else pass.
Let the loop run through and print out the final value of V1.

Below you can find the implementation of the above-mentioned approach:
Examples 1:

Python3

import math
 
# input list
List = [2, 3, 4, 4, 4 ]
 
max1 = 0
for i in range(len(List)-1):
   
  # use math.gcd() function
  gcd1 = math.gcd(List[i], List[i + 1])
  if(gcd1>max1):
    max1 = gcd1
     
# print max1
# as the result
print(max1)

Output:

Explanation: For the given array one of the subarrays having maximum gcd is[3, 5] which has gcd 4.

Time Complexity: O(n * log(min(a, b))), as it iterates through the input list once of size n, and gcd() method takes log(min(a,b)) time.
Auxiliary Space: O(log(n)), as it uses recursion and the maximum depth of recursion is log(n).

Example 2:

Python3

import math
 
# input list
List = [3, 7, 2, 9, 18, 5, 1, 13 ]
 
max1 = 0
for i in range(len(List)-1):
   
  # use math.gcd() function
  gcd1 = math.gcd(List[i], List[i + 1])
  if(gcd1>max1):
    max1 = gcd1
     
# print max1
# as the result
print(max1)