LeetCode 1929. Concatenation of Array

Description

https://leetcode.com/problems/concatenation-of-array/

Given an integer array nums of length n, you want to create an array ans of length 2n where ans[i] == nums[i] and ans[i + n] == nums[i] for 0 <= i < n (0-indexed).

Specifically, ans is the concatenation of two nums arrays.

Return the array ans.

Example 1:

Input: nums = [1,2,1]
Output: [1,2,1,1,2,1]
Explanation: The array ans is formed as follows:
- ans = [nums[0],nums[1],nums[2],nums[0],nums[1],nums[2]]
- ans = [1,2,1,1,2,1]

Example 2:

Input: nums = [1,3,2,1]
Output: [1,3,2,1,1,3,2,1]
Explanation: The array ans is formed as follows:
- ans = [nums[0],nums[1],nums[2],nums[3],nums[0],nums[1],nums[2],nums[3]]
- ans = [1,3,2,1,1,3,2,1]

Constraints:

  • n == nums.length
  • 1 <= n <= 1000
  • 1 <= nums[i] <= 1000

Explanation

Simply add all elements twice.

Python Solution

class Solution:
    def getConcatenation(self, nums: List[int]) -> List[int]:
        results = []
        
        for i in range(len(nums)):
            results.append(nums[i])

        for i in range(len(nums)):
            results.append(nums[i])
        
        return results
  • Time Complexity: O(N).
  • Space Complexity: O(N).

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