[JS] Permutations II

🔒 문제 (LeetCode 47)

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

Constraints:

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

 

🌊 입출력

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]]

 

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🔑 해결

🌌 알고리즘 - backtracking (DFS)

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var permuteUnique = function(nums) {
    nums.sort((a, b) => a-b)
    const result = []
    let visited = new Array(nums.length).fill(false)
    
    const backtracking = (per, visited) => {        
        if(per.length === nums.length) {
            result.push([...per])
            return
        }
        
        for(let i = 0; i < nums.length; i++) {
            if(visited[i]) continue
            
            if(i > 0 && nums[i] === nums[i-1] && visited[i-1]) continue
            
            visited[i] = true
            per.push(nums[i])
            
            backtracking(per, visited)
            
            visited[i] = false
            per.pop()

        }
        
    }
    
    backtracking([], visited)
    
    return result
};