[Algorithm] 88. Merge Sorted Array

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:

• The number of elements initialized in nums1 and nums2 are m and n respectively.
• You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2.

Example:

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

Output: [1,2,2,3,5,6]

/**
 * @param {number[]} nums1
 * @param {number} m
 * @param {number[]} nums2
 * @param {number} n
 * @return {void} Do not return anything, modify nums1 in-place instead.
 */
var merge = function(nums1, m, nums2, n) {
    while (m > 0 && n > 0) {
        const n2 = nums2[n - 1];
        const n1 = nums1[m - 1];
        let toSave;
        
        if (n2 > n1) {
            nums1[m + n - 1] = n2;
            n = n - 1;
        } else {
            nums1[m + n - 1] = n1;
            m = m - 1;
        }
    }
    
    if (n > 0 && m === 0) {
        while (n > 0) {
            const n2 = nums2[n - 1];
            nums1[n - 1] = n2;
            n--;
        }
    }
};