Algorithm Puzzles: Merge Sorted Array

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Algorithm Puzzles everyday every week sometimes: Merge Sorted Array

Puzzle

Puzzle from leetcode:

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Solution

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class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        if(m == 0) {
            nums1 = nums2;
            return;
        }

        if(n == 0) {
            return;
        }

        auto ret = std::vector<int>();
        int i = 0, j = 0;

        for(; i < m && j < n;){
            if(nums1[i] <= nums2[j]) {
                ret.push_back(nums1[i]);
                i++;
            }else{
                ret.push_back(nums2[j]);
                j++;
            }
        }

        if(i != m) {
            ret.insert(ret.end(), nums1.begin() + i, nums1.begin() + m);
        }

        if(j != n) {
            ret.insert(ret.end(), nums2.begin() + j, nums2.end());
        }

        nums1 = ret;
    }
};

Not sure why this brutal force solution can beat 100% people…