LeetCode - Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

 

Example 1:

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

Example 2:

Input: nums = [0,1]
Output: [[0,1],[1,0]]

Example 3:

Input: nums = [1]
Output: [[1]]

 

Constraints:

• 1 <= nums.length <= 6
• -10 <= nums[i] <= 10
• All the integers of nums are unique.

 

ChatGPT's Solution:

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        def backtrack(start: int):
            if start == len(nums):
                result.append(nums[:])
                return
            
            for i in range(start, len(nums)):
                nums[start], nums[i] = nums[i], nums[start]  # Swap
                backtrack(start + 1)
                nums[start], nums[i] = nums[i], nums[start]  # Swap back
        
        result = []
        backtrack(0)
        return result