Array Two Pointers

Description:

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:

You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.

我现在意识到我的智商非常低...刚开始一直纠结于从前往后排，想的头都要炸了...看了眼discuss，感叹人类的智慧啊（主要还是题主太蠢）从后往前排的话，工作量小太多太多了！！

Solution:

public class Solution {

    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 (i >= 0 && j >= 0) {

            if (nums1[i] > nums2[j]) {

                nums1[k--] = nums1[i--];

            } else {

                nums1[k--] = nums2[j--];

            }

        }

        while (j >= 0) {

            nums1[k--] = nums2[j--];

        }

        while (i >= 0) {

            nums1[k--] = nums1[i--];

        }

    }

}