#2447 - Number of Subarrays With GCD Equal to K

Medium • View on LeetCode • View on GitHub

Problem Description

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.

Solution

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
var subarrayGCD = function(nums, k) {
  let result = 0;
  for (let start = 0; start < nums.length; start++) {
    let currentGCD = nums[start];
    for (let end = start; end < nums.length; end++) {
      currentGCD = gcd(currentGCD, nums[end]);
      if (currentGCD === k) {
        result++;
      }
    }
  }

  return result;

  function gcd(a, b) {
    while (b) {
      a %= b;
      [a, b] = [b, a];
    }
    return a;
  }
};