Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
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.
nums1 = [1,2,3,0,0,0], m = 3
nums2 = [2,5,6], n = 3