LeetCode (3) - Shuffle an Array (파이썬, python)

❓ 문제

Given an integer array nums, design an algorithm to randomly shuffle the array.

Implement the Solution class:

• Solution(int[] nums) Initializes the object with the integer array nums.
• int[] reset() Resets the array to its original configuration and returns it.
• int[] shuffle() Returns a random shuffling of the array.

Example 1:

Input
["Solution", "shuffle", "reset", "shuffle"]
[[[1, 2, 3]], [], [], []]
Output
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

Explanation
Solution solution = new Solution([1, 2, 3]);
solution.shuffle();    // Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must be equally likely to be returned. Example: return [3, 1, 2]
solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]
solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]

Constraints:

• 1 <= nums.length <= 200
• -10^6 <= nums[i] <= 10^6
• All the elements of nums are unique.
• At most 5 * 10^4 calls will be made to reset and shuffle.

---

Given Code

class Solution:

    def __init__(self, nums: List[int]):
        

    def reset(self) -> List[int]:
        """
        Resets the array to its original configuration and return it.
        """
        

    def shuffle(self) -> List[int]:
        """
        Returns a random shuffling of the array.
        """
        


# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()

---

접근법

init과 reset, shuffle을 적절히 이용하면 됩니다.

import random
class Solution:

    def __init__(self, nums: List[int]):
        self.data = nums

    def reset(self) -> List[int]:
        """
        Resets the array to its original configuration and return it.
        """
        return self.data
        

    def shuffle(self) -> List[int]:
        """
        Returns a random shuffling of the array.
        """
        output = []
        datacopy = self.data.copy()
        for _ in range(len(self.data)):
            index = random.randint(0, len(datacopy) - 1)
            output.append(datacopy[index])
            del datacopy[index]
        return output


# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()

init의 인자인 배열 nums를 self.data로 받아줍니다.

reset의 경우 오리지날 nums인 self.data를 반환하게 했습니다.

shuffle의 경우 random.randint를 사용했습니다. self.data를 복사한 datacopy에서 랜덤하게 하나씩 빼서 output이라는 배열로 지정한 뒤 output을 반환하게 했습니다. random.randint로 무작위의 datacopy의 index를 뽑아냈습니다.