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2470. Number of Subarrays With LCM Equal to K 👍

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  int subarrayLCM(vector<int>& nums, int k) {
    int ans = 0;

    for (int i = 0; i < nums.size(); ++i) {
      int runningLcm = nums[i];
      for (int j = i; j < nums.size(); ++j) {
        runningLcm = std::lcm(runningLcm, nums[j]);
        if (runningLcm > k)
          break;
        if (runningLcm == k)
          ++ans;
      }
    }

    return ans;
  }
};

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class Solution {
  public int subarrayLCM(int[] nums, int k) {
    int ans = 0;

    for (int i = 0; i < nums.length; ++i) {
      int runningLcm = nums[i];
      for (int j = i; j < nums.length; ++j) {
        runningLcm = lcm(runningLcm, nums[j]);
        if (runningLcm > k)
          break;
        if (runningLcm == k)
          ++ans;
      }
    }

    return ans;
  }

  private int gcd(int a, int b) {
    return b == 0 ? a : gcd(b, a % b);
  }

  private int lcm(int a, int b) {
    return a * (b / gcd(a, b));
  }
}

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class Solution:
  def subarrayLCM(self, nums: List[int], k: int) -> int:
    ans = 0

    for i, runningLcm in enumerate(nums):
      for j in range(i, len(nums)):
        runningLcm = math.lcm(runningLcm, nums[j])
        if runningLcm > k:
          break
        if runningLcm == k:
          ans += 1

    return ans