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# 000046-Permutations

### Problem

<https://leetcode.com/problems/permutations/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

backtracking

```python
class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        res = []
        def backtrack(nums, path=[]):
            if len(path) == len(nums):
                res.append(path[:])
                return
            for num in nums:
                if num in path:
                    continue
                path.append(num)
                backtrack(nums, path)
                path.pop() # backtrack
        backtrack(nums, [])

        return res
```