Permutations

class Solution:
    def __init__(self):
        self.res = []
        self.path = []
        self.used = []

    def backtrack(self, nums):
        if len(self.path) == len(nums):
            self.res.append(self.path.copy())
            return None
        for i in range(len(nums)):
            if self.used[i]:
                continue
            self.path.append(nums[i])
            self.used[i] = True
            self.backtrack(nums)
            self.used[i] = False
            self.path.pop()

    def permute(self, nums: List[int]) -> List[List[int]]:
        self.used = [False] * len(nums)
        self.backtrack(nums)
        return self.res

Permutations

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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.