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,If nums = [1,2,3], a solution is:
[ [3], [1], [2], [1,2,3], [1,3], [2,3], [1,2], [] ]Show Company Tags Show Tags Show Similar Problems
public class Solution { public List<List<Integer>> subsets(int[] nums) { List<List<Integer>> result = new ArrayList<List<Integer>>(); ArrayList<Integer> list = new ArrayList<Integer>(); if(nums==null||nums.length==0) return result; Arrays.sort(nums); subhelper(nums,result,list,0); return result; } public void subhelper(int[] nums, List<List<Integer>>result, ArrayList<Integer> list, int pos) { result.add(new ArrayList<Integer>(list)); for(int i=pos;i<nums.length;i++) { list.add(nums[i]); subhelper(nums,result,list,i+1); list.remove(list.size()-1); } } }
算法复杂度：O(2^n)
假设n=3时，C30+C31+C32+C33 = 8 = (1+1)^3
即（1+1）^n = 2^n
转载于:https://www.cnblogs.com/hygeia/p/5180873.html
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