78. Subsets java solutions

Given a set of distinct integers, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]


 1 public class Solution {
 2     List<List<Integer>> ans = new ArrayList<>();
 3     public List<List<Integer>> subsets(int[] nums) {
 4         List<Integer> list = new ArrayList<>();
 5         ans.add(list);
 6         for(int i = 0; i < nums.length; i++){//按照 取subset的长度 一个个遍历一遍
 7             findSubset(list,nums,i+1,0);
 8         }
 9         return ans;
10     }
11     
12     public void findSubset(List<Integer> list, int[] nums, int k, int s){
13         if(k == 0){
14             List<Integer> tmp = new ArrayList<>(list);
15             ans.add(tmp);
16             return;
17         }
18         for(int i = s; i < nums.length; i++){
19             list.add(nums[i]);
20             findSubset(list,nums,k-1,i+1);
21             list.remove(list.size()-1);
22         }
23     }
24 }

一个小的总结帖，二刷再试下其他解法。

https://discuss.leetcode.com/topic/46159/a-general-approach-to-backtracking-questions-in-java-subsets-permutations-combination-sum-palindrome-partitioning

posted @ 2016-07-14 11:34  Miller1991  阅读(266)  评论(0)  编辑  收藏  举报