【LeetCode OJ 078】Subsets淺析

【LeetCode OJ 078】Subsets淺析

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

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

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

   

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

  解題思路：搜了一下網上的解題思路，有一個感覺很巧妙。大致的思路是這樣的，一個數組的子集個數是這個數組的長度的n次方(2^n)，例如a[2]={1,2}，子集個數就是2^2=4，二進制表示為00，01,10,11，分別表示空集、{1}、{2}、{12}，具體的實現代碼如下：

   

   

  public class Solution
  {
  	public List> subsetsWithDup(int[] nums) 
  	{
  		List> result=new ArrayList>();
  		//先對數組進行排序
  		Arrays.sort(nums);
  		int n=nums.length;
  		//1< list=new ArrayList();
  			for(int j=0;j