Number of subarrays with gcd equal to k

December 3, 2022

math-and-geometry

Problem URL: Number of subarrays with gcd equal to k

We will take every possible subarray of the input array and calculate the gcd of the subarray. If the gcd is equal to k, we will increment the count of such subarrays.

class Solution:
    def subarrayGCD(self, nums: List[int], k: int) -> int:
        def gcd(a: int, b: int) -> int:
            while a and b:
                a, b = b, a%b
            return a or b

        count = 0
        n = len(nums)
        for i in range(n):
            tmp_gcd = 0
            for j in range(i,n):
                tmp_gcd = gcd(tmp_gcd, nums[j])

                if tmp_gcd == k:
                    count += 1
                elif tmp_gcd < k:
                    break

        return count

Time complexity: O(n^2)
Space complexity: O(1)