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 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]

Constraints:

-10^9 <= nums1[i], nums2[i] <= 10^9 nums1.length == m + n nums2.length == n Solution.

class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        // index for m
        int im = m -1;
        // index for n
        int in = n -1;
        // index for result
        int ir = m + n -1;
        
        for (;ir >= 0; ir --){
            
            if (im < 0){
                // If one of the array is all cleared, use the other
                nums1[ir] = nums2[in--];
            } else if (in < 0){
                nums1[ir] = nums1[im--];
            } else if (nums1[im] > nums2[in]){
                // Otherwise, pick the greater one.
                nums1[ir] = nums1[im--];
            } else {
                nums1[ir] = nums2[in--];
            }
        }
        
    }
}