LeetCode 88. Merge Sorted Array

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 andnums2 are m and n respectively.
代码：

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        for(int i=0; i<n; i++) {
            // /!\ Mind that m might be less than the actual size of nums1
            if(nums1.size() < m + i + 1)
                nums1.push_back(-1);
        }
        int pos_1 = m-1;
        int pos_2 = n-1;
        int end = m + n - 1;
        while(pos_1 >= 0 && pos_2 >= 0) {
            if(nums1[pos_1] > nums2[pos_2]) {
                nums1[end] = nums1[pos_1];
                pos_1--;
            } else {
                nums1[end] = nums2[pos_2];
                pos_2--;
            }
            end--;
        }
        while(pos_2 >= 0){
            nums1[end--] = nums2[pos_2--];
        }
    }
};