LeetCode 78. Subsets

原创于 2017-07-13 01:26:55 发布 · 342 阅读

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本文介绍了一个算法问题：如何找出给定整数数组的所有可能子集，并确保结果中不含重复子集。通过递归方法实现解决方案，该算法适用于面试场景。

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],
  []
]

Seen this question in a real interview before?

输出给出的数组的全部子数组，一道np问题，暴力递归即可

public class Solution {
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>>res = new ArrayList<List<Integer>>();
        List<Integer>list = new ArrayList<Integer>();
        Arrays.sort(nums);
        helper(res,list,nums,0);
        return res;
    }
    public void helper(List<List<Integer>>res,List<Integer>list,int[]nums,int n){
        if(n==nums.length){
            res.add(new ArrayList<Integer>(list));
            return ;
        }
        helper(res,list,nums,n+1);
        list.add(nums[n]);
        helper(res,list,nums,n+1);
        list.remove(list.size()-1);
        return ;       
    }
}