Leetcode 88. Merge Sorted Array(easy)

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.

 剑指offer的经典题，利用指针从后边开始往前一个一个排列数字。

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        if (n == 0)  return;
        if (m == 0) {
            for (int i = 0; i < n; i++){
                nums1[i] = nums2[i];
            }
            return;
        }
        int p = m + n - 1, p1 = m - 1, p2 = n - 1;
        while (p1 >= 0 && p2 >= 0){
            int maxval = max(nums1[p1], nums2[p2]);
            if (maxval == nums1[p1]){
                p1--;
            }else{
                p2--;
            }
            nums1[p] = maxval;
            p--;
        }
        while (p2 >= 0){
            nums1[p--] = nums2[p2--];
        }
        return;
    }
};