Permutations II

Description

Given a collection of numbers that might contain duplicates, return all possible unique permutations.

Example:

Input: [1,1,2]
Output:
[
  [1,1,2],
  [1,2,1],
  [2,1,1]
]

Solution(javascript)

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
const permuteUnique = (nums) => {
  const result = []
  const aux = (list = [], current = []) => {
    if (list.length === 0) {
      result.push(current)
    }
    const visited = {}
    for (let i = 0; i < list.length; i++) {
      if (!visited[list[i]]) {
        visited[list[i]] = true
        aux(list.filter((v, index) => index !== i), [...current, list[i]])
      }
    }
  }
  aux(nums)
  return result
}