46. Permutations

Problem Link

Description

---

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.

Solution

---

Python3

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        N = len(nums)
        visited = [False] * N
        res = []
 
        def go(curr):
            if len(curr) == N:
                res.append(curr[:])
                return
            
            for j in range(N):
                if not visited[j]:
                    visited[j] = True
                    curr.append(nums[j])
                    go(curr)
                    curr.pop()
                    visited[j] = False
        
        go([])
        return res