1470_shuffle-the-array.md

Problem

Given the array nums consisting of 2n elements in the form [x1,x2,...,xn,y1,y2,...,yn].

Return the array in the form [x1,y1,x2,y2,...,xn,yn].

Example 1:

Input: nums = [2,5,1,3,4,7], n = 3
Output: [2,3,5,4,1,7] 
Explanation: Since x1=2, x2=5, x3=1, y1=3, y2=4, y3=7 then the answer is [2,3,5,4,1,7].

Example 2:

Input: nums = [1,2,3,4,4,3,2,1], n = 4
Output: [1,4,2,3,3,2,4,1]

Example 3:

Input: nums = [1,1,2,2], n = 2
Output: [1,2,1,2]

Constraints:

1 <= n <= 500
nums.length == 2n
1 <= nums[i] <= 10^3

Attempt 1

class Solution:
    def shuffle(self, nums: List[int], n: int) -> List[int]:
        num1= []
        num2= []
        ans= []
        for i, num in enumerate(nums):
            if (i < n):
                num1.append(num)
            else:
                num2.append(num)

        for j in range(2*n):
            if (j%2 == 1):
                ans.append(num2.pop(0))
            else: 
                ans.append(num1.pop(0))
        return ans

• Time Complexity: O(n)
• Space Complexity: O(n)

Optimised Solution

class Solution:
    def shuffle(self, nums: List[int], n: int) -> List[int]:
        ## APPROACH : GREEDY ##
        ans = []
        for i in range(n):
            ans.append(nums[i])
            ans.append(nums[i+n])
        return ans

• Time Complexity: O(n)
• Space Complexity: O(n)