88 Merge Sorted Array

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 greater or 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]

example

nums1 = [1,2,4,5,6,0], m = 5
nums2 = [3],           n = 1

class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int ptr1 = m - 1;
        int ptr2 = n - 1;
        int index = m + n - 1;
        while (index >= 0) {
            if (ptr1 >= 0 && ptr2 >= 0 && nums1[ptr1] >= nums2[ptr2]) {
                nums1[index--] = nums1[ptr1--];
            }else if (ptr1 >= 0 && ptr2 >= 0 && nums1[ptr1] < nums2[ptr2]){
                nums1[index--] = nums2[ptr2--];
            }else if(ptr1 >= 0) {
                nums1[index--] = nums1[ptr1--];
            }else if (ptr2 >= 0) {
                nums1[index--] = nums2[ptr2--];
            }
        }
    }
}

Edward

class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int ptr1 = m - 1;
        int ptr2 = n - 1;
        int index = m + n - 1;
        while (ptr1 >= 0 && ptr2 >= 0) {
            nums1[index--] = nums1[ptr1] >= nums2[ptr2] ? nums1[ptr1--] : nums2[ptr2--];
        }
        while (ptr2 >= 0) {
            nums1[index--] = nums2[ptr2--];
        }
    }
}