88 Merge Sorted Array

Problem Statement

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
Output: [1,2,2,3,5,6]


Three Pointers and assigning values into nums from end. P1 looks at the last entry before the 0 values, P2 at the last entry in nums2 and P3 looks at (m+ n - 1). From there it is a while loop through the array that assigns whatever value at position of the pointers is greater to nums1[p3]. All pointers will be shifted accordingly.
Finally we need another while loop that handles remaining items in nums2.


var twoSum = function(nums, target) {
    let p1 = m - 1; // Pointer for nums1 (excluding trailing zeros)
    let p2 = n - 1; // Pointer for nums2
    let p3 = m + n - 1; // Pointer for the merged result

    while (p1 >= 0 && p2 >= 0) {
        if (nums1[p1] > nums2[p2]) {
            nums1[p3] = nums1[p1];
        } else {
            nums1[p3] = nums2[p2];

    // If there are remaining elements in nums2, copy them to nums1
    while (p2 >= 0) {
        nums1[p3] = nums2[p2];




Two Pointers