Number of Subarrays With GCD Equal to K — LeetCode 2447 Python Solution

The problem

Given an integer array nums and an integer k, return the number of subarrays of nums where the greatest common divisor of the subarray's elements is k. A subarray is a contiguous non-empty sequence of elements within an array.

Example

Input

nums = [9,3,1,2,6,3], k = 3

Output

4

Explanation

The subarrays of nums where 3 is the greatest common divisor of all the subarray's elements are:

Python solution

class Solution:
    def subarrayGCD(self, nums: List[int], k: int) -> int:
        ans = 0
        for i in range(len(nums)):
            g = 0
            for x in nums[i:]:
                g = gcd(g, x)
                ans += g == k
        return ans

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 2447. Number of Subarrays With GCD Equal to K is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math and Number Theory.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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