MergeSortedArray.java

/* Example 1 : Input : nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
 * Output : [1,2,2,3,5,6]
 * Explanation : The arrays we are merging are [1,2,3] and [2,5,6].
 * The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1.
 * 
 * Example 2 : Input : nums1 = [1], m = 1, nums2 = [], n = 0
 * Output : [1]
 * Explanation : The arrays we are merging are [1] and [].
 * The result of the merge is [1].
 * 
 * Example 3 : Input : nums1 = [0], m = 0, nums2 = [1], n = 1
 * Output : [1]
 * Explanation : The arrays we are merging are [] and [1].
 * The result of the merge is [1].
 * Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.*/ 

class MergeSortedArray {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int i = m-1; 
        int j = n-1; 
        int k = m+n-1;

        while(j>=0){
            if(i>=0 && nums1[i] > nums2[j]){
                nums1[k] = nums1[i];
                k--; 
                i--; 
            }else{
                nums1[k] = nums2[j];
                k--; 
                j--;
            }
        }
    }

}