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46. Permutations

Array Backtracking

Problem - Permutations

Medium

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.

Solutions

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class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        n = len(nums)
        values = [0] * n
        result = []
        visited = [False] * n

        def dfs(i: int):
            if i >= n:
                result.append(values[:])
                return

            for j, val in enumerate(nums):
                if not visited[j]:
                    visited[j] = True
                    values[i] = val
                    dfs(i + 1)
                    visited[j] = False
        dfs(0)
        return result

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 17.9 MB (59.36%)