491. increasing subsequences

Set is used for this question.
Because there is no sort, there may be repeated things in the future.

Https://leetcode.com/problems/increasing-subsequences/discuss/97130/Java-20-lines-backtracking-solution-using-set-beats-100.

 

 

 1 class Solution { 2     Set<List<Integer>> res = new HashSet<>(); 3     public List<List<Integer>> findSubsequences(int[] nums) { 4         if(nums.length == 0) new ArrayList<>(res); 5         visited = new boolean[nums.length]; 6         backtrack(nums, new ArrayList<>(), 0); 7         return new ArrayList<>(res); 8         9     }10     11     public void backtrack(int[] nums, List<Integer> list, int pos){12         if(list.size() > 1){13             res.add(new ArrayList<>(list));14         }15         16         for(int i = pos; i < nums.length; i++){17             if(list.size() != 0 && (nums[i] < list.get(list.size()-1))){18                 continue;19             }else{20                 list.add(nums[i]);21                 visited[i] = true;22                 backtrack(nums, list, i+1);23                 visited[i] = false;24                 list.remove(list.size()-1);25             }26             27             28         }         29         30     }31 }

 

491. increasing subsequences