Merge Sorted Array

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

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

Solution. Loop from end to start. In this way, we can do this in-place.

public static void merge(int[] nums1, int m, int[] nums2, int n) {
    int k = m + n - 1;
    m--;
    n--;
    while (m >= 0 && n >= 0) {
        if (nums1[m] > nums2[n]) {
            nums1[k--] = nums1[m--];
        }
        else {
            nums1[k--] = nums2[n--];
        }
    }
    while (m >= 0) {
        nums1[k--] = nums1[m--];
    }
    while (n >= 0) {
        nums1[k--] = nums2[n--];
    }
}

Check my code on github.