Median of Two Sorted Arrays

Description

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

Follow up: 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(javascript)

/**
 * @param {number[]} nums1
 * @param {number[]} nums2
 * @return {number}
 */
const findMedianSortedArrays = (nums1, nums2) => {
  const merge = (xs1, xs2) => {
    if (!xs1 || !xs1.length) {
      return xs2
    }
    if (!xs2 || !xs2.length) {
      return xs1
    }
    const [hd1, ...rest1] = xs1
    const [hd2, ...rest2] = xs2
    return hd1 <= hd2 ? [hd1, ...merge(rest1, xs2)] : [hd2, ...merge(xs1, rest2)]
  }
  const nums = merge(nums1, nums2)
  const middle = Math.floor((nums.length-1) / 2)

  return (middle * 2 === (nums.length-1)) ?  nums[middle] : ((nums[middle] + nums[middle + 1]) / 2) 
}