1929. Concatenation of Array - Java Solution Beats 94% in Runtime (EXTREMELY LOGICAL SOLUTION)

#array #java #leetcode #programming

For a more in-depth explanation, please view my GitHub repository: https://github.com/VerisimilitudeX/LeetCode

Intuition

The problem is to create a new array that is the concatenation of the given array with itself. For example, if the given array is [1, 2, 3], the new array should be [1, 2, 3, 1, 2, 3].

Approach

To create the new array, we can first allocate an array of double the length of the given array. Then, we can use a for loop to copy each element of the given array to the new array twice: once at the original index and once at the index plus the length of the given array.

Complexity

Time complexity: The time complexity of this code is $$O(n)$$
where n is the length of the given array. This is because we need to iterate over each element of the given array once and copy it to the new array twice.
Space complexity: The space complexity of this code is $$O(n)$$
where n is the length of the given array. This is because we need to allocate a new array of double the size of the given array.

Code

class Solution {
    public int[] getConcatenation(int[] nums) {
        short len = (short) nums.length;
        int[] newNums = new int[len * 2];
        for (short i = 0; i < len; i++) {
            newNums[i] = nums[i];
            newNums[i + len] = nums[i];
        }
        return newNums;
    }
}