LeetCode-in-All

4. Median of Two Sorted Arrays

Hard

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.

The overall run time complexity should be O(log (m+n)).

Example 1:

Input: nums1 = [1,3], nums2 = [2]

Output: 2.00000

Explanation: merged array = [1,2,3] and median is 2.

Example 2:

Input: nums1 = [1,2], nums2 = [3,4]

Output: 2.50000

Explanation: merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5.

Example 3:

Input: nums1 = [0,0], nums2 = [0,0]

Output: 0.00000

Example 4:

Input: nums1 = [], nums2 = [1]

Output: 1.00000

Example 5:

Input: nums1 = [2], nums2 = []

Output: 2.00000

Constraints:

• nums1.length == m
• nums2.length == n
• 0 <= m <= 1000
• 0 <= n <= 1000
• 1 <= m + n <= 2000
• -106 <= nums1[i], nums2[i] <= 106

Solution

defmodule Solution do
  @spec find_median_sorted_arrays(nums1 :: [integer], nums2 :: [integer]) :: float
  def find_median_sorted_arrays(nums1, nums2) do
    list = Enum.sort(nums1 ++ nums2)

    cond do
        length(list) === 1 -> 
            Enum.at(list, 0)

        rem(length(list), 2) === 0 -> 
            start_index = trunc(length(list) / 2 - 1)
            (Enum.at(list, start_index) + Enum.at(list, start_index + 1)) / 2

        true -> 
            start_index = div(length(list), 2)
            Enum.at(list, start_index)
    end
  end
end

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