[LeetCode January Challange] Day 11 - Merge Sorted Array

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

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 equal to m + n) to hold additional elements from nums2.

Example 1:

Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
Output: [1,2,2,3,5,6]

Example 2:

Input: nums1 = [1], m = 1, nums2 = [], n = 0
Output: [1]

Constraints:

• 0 <= n, m <= 200
• 1 <= n + m <= 200
• nums1.length == m + n
• nums2.length == n
• -10^9 <= nums1[i], nums2[i] <= 10^9

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Solution

Time complexity : O(m+n)
Space complexity : O(1)

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        int p1 = m-1, p2 = n-1, p = nums1.size()-1;
        while (0 <= p2 && 0 <= p1)
            nums1[p--] = (nums1[p1] < nums2[p2]) ? nums2[p2--] : nums1[p1--];
        
        while (0 <= p2) nums1[p--] = nums2[p2--];
    }
};