2447. Number of Subarrays With GCD Equal to K

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.

The greatest common divisor of an array is the largest integer that evenly divides all the array elements.

class Solution {
public:
    int subarrayGCD(vector<int>& nums, int k) {
        int res = 0;
        for(int i = 0; i < nums.size(); i++) {
            int g = nums[i];
            if(g == k) res += 1;
            for(int j = i + 1; j < nums.size() and g % k == 0; j++) {
                g = __gcd(g,nums[j]);
                if(g == k) res += 1;
            }
        }
        return res;
    }
};