47. Permutations II
https://leetcode.com/problems/permutations-ii/
Related problems
46-permutations
78-subsets
90-subsets-ii
39-combination-sum
---
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] ]---
Related problems
46-permutations
78-subsets
90-subsets-ii
39-combination-sum
---
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| class Solution { | |
| public List<List<Integer>> permuteUnique(int[] nums) { | |
| Arrays.sort(nums); | |
| List<List<Integer>> ans = new ArrayList<List<Integer>>(); | |
| dfs(nums, new ArrayList<Integer>(), new HashSet<Integer>(), ans); | |
| return ans; | |
| } | |
| private void dfs(int[] nums, List<Integer> prefix, Set<Integer> visited, List<List<Integer>> ans) { | |
| if (prefix.size() == nums.length) { | |
| ans.add(new ArrayList<Integer>(prefix)); | |
| return; | |
| } | |
| for (int i = 0; i < nums.length; i++) { | |
| if (visited.contains(i) || (i > 0 && nums[i] == nums[i - 1] && !visited.contains(i - 1))) { | |
| continue; | |
| } | |
| visited.add(i); | |
| prefix.add(nums[i]); | |
| dfs(nums, prefix, visited, ans); | |
| prefix.remove(prefix.size() - 1); | |
| visited.remove(i); | |
| } | |
| } | |
| } |
