package code; /* * 78. Subsets * 题意：求数组子集 * 难度：Medium * 分类：Array, Backtracking, Bit Manipulation * 思路：回溯法 * Tips：和lc46,39作比较.要找出子集，所以每次backtracking直接添加进res */ import java.util.ArrayList; import java.util.List; public class lc78 { public static void main(String[] args) { int[] nums= {1,2,3}; System.out.println(subsets(nums).toString()); } public static List> subsets(int[] nums) { List> res = new ArrayList>(); res.add(new ArrayList<>()); if(nums.length==0) return res; backtracking(res,nums,new ArrayList(),-1); return res; } public static void backtracking(List> res, int[] nums, List l, int start){ if(start>=nums.length) return; for (int i = start+1; i < nums.length ; i++) { l.add(nums[i]); res.add(new ArrayList(l)); backtracking(res,nums,l,i); l.remove((Integer)nums[i]); } } }