JavaScriptMedianOfTwoSortedArrays.md

JavaScript Median of Two Sorted Arrays

Challenge

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)).

1^st Example

Input: nums1 = [1,3], nums2 = [2]
Output: 2.00000
Explanation: merged array = [1,2,3]
             and median is 2.

2^nd Example

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.

Constraints

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

Solution

const findMedianSortedArrays = (nums1, nums2) => {
    const merge = [...nums1, ...nums2].sort((a, b) => a - b),
              n = merge.length;

    if (n < 2) {
        return merge.join('');
    }

    if (n % 2 === 0) {
        const mid = n / 2;

        return (merge[mid - 1] + merge[mid]) / 2;
    } else {
        const mid = Math.floor(n / 2);

        return merge[mid];
    }
};

Explanation

I've written a function called findMedianSortedArrays that takes in two arrays, nums1 and nums2. The purpose of this function is to merge and sort the arrays, and then find the median of the merged array.

Inside the function, the arrays nums1 and nums2 are merged into a new array called merge using the spread operator. The merge array is then sorted in ascending order using the sort method with a comparison function that subtracts one element from another.

The length of the merge array is stored in a variable called n. If the length is less than 2, indicating that there is only one element or no elements in the array, the function joins the elements of the merge array into a string and returns it.

If the length of the merge array is even, the function calculates the middle index by dividing the length by 2. The median is then calculated by adding the element at the index mid - 1 and the element at the index mid, and dividing the sum by 2. This value is returned as the median.

If the length of the merge array is odd, the function calculates the middle index using the Math.floor function to round down the division of the length by 2. The element at the index mid of the merge array is returned as the median.

In summary, the findMedianSortedArrays function takes two arrays, merges and sorts them, and then finds the median of the merged array.

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