Permutations II

Problem statement

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

Example 1:

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

Example 2:

Input: nums = [1,2,3]Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Constraints:

• 1 <= nums.length <= 8
• -10 <= nums[i] <= 10

My solution

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var permuteUnique = function(nums) {
    const set = new Set(nums)
    const map = new Map();
    
    for (const num of nums) {
        map.set(num, (map.get(num) || 0) + 1)
    }
    
    const result = []
    
    
    function parse(combination) {
        // console.log(combination)
        if (combination.length === nums.length) {
            result.push([...combination])
            return;
        } else {
            for (const num of set.values()) {
                if (map.get(num)) {
                    combination.push(num)
                    map.set(num, map.get(num) - 1)
                    parse(combination)
                    combination.pop();
                    map.set(num, map.get(num) + 1)
                }
            }
        }
    }
                
    parse([])
    
    return result;
};