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###### tags: `Leetcode`
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# Leetcode 1470. Shuffle the Array

[link](https://leetcode.com/problems/shuffle-the-array/description/)

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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

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題意: 給你一個數組`nums`，數組中有 2n 個元素，按`[x1,x2,...,xn,y1,y2,...,yn]`的格式排列。請你將數組按`[x1,y1,x2,y2,...,xn,yn]`格式重新排列，返回重排後的數組。

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Here, we may use two pointers to identify the first element of each array, iterate the array, and then store the elements in the new array by order.

#### Solution 1

class Solution:
    def shuffle(self, nums: List[int], n: int) -> List[int]:
        l, r = 0, n
        lst = []
        while r < len(nums):
            lst.append(nums[l])
            lst.append(nums[r])
            l += 1
            r += 1

        return lst

O(T): O(n)
O(S): O(n)

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