46.Permutations

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

analyze

该问题可以看成为一道排列问题, 排列问题的一种常见解法是回溯法:

* 1
  * 2
    * 3
  * 3
    * 2
* 2
  * 1
    * 3
  * 3
    * 1
* 3
  * 1
    * 2
  * 2
    * 1

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var permute = function (nums) {
  const res = []
  backtracking(nums, [], res)
  return res
};

var backtracking = function(nums, temp, res) {
  if (temp.length === nums.length) {
    res.push([...temp])
    return
  }

  for (let i = 0; i < nums.length; i++) {
    if (!temp.includes(nums[i])) {
      temp.push(nums[i])
      backtracking(nums, temp, res)
      temp.pop(nums[i])
    } else {
      continue
    }
  }
}