20Merge two sorted arrays

Implement merge(nums1, m, nums2, n). nums1 and nums2 are sorted in ascending order. nums1 has a length of m + n: the first m items are real values and the last n are placeholders (0). Merge nums2 into nums1 in place so nums1 ends up sorted.

const nums1 = [1, 2, 3, 0, 0, 0];
merge(nums1, 3, [2, 5, 6], 3);
nums1; // [1, 2, 2, 3, 5, 6]

Requirements

• Change nums1 in place; do not return a new array.
• Use O(1) extra space.
• Solve it in O(m + n) time.