Permutations

46. Permutations

Difficulty: Medium

Related Topics: Array, Backtracking

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]]

Code:

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        res = []
        n = len(nums)
        check = [False] * n

        def recur(num, tmp):
            if num == n:
                res.append(tmp.copy())
                return
                
            for i in range(n):
                if check[i] == False:
                    check[i] = True
                    tmp.append(nums[i])
                    recur(num + 1, tmp)
                    check[i] = False
                    tmp.pop()
        
        recur(0, [])
        return res