import java.util.Arrays; import java.util.LinkedList; import java.util.List; public class SubsetsII { public List> subsetsWithDup(int[] nums) { List> result = new LinkedList>(); if (nums.length == 0) { return result; } /** * 千万别掉了排序 */ Arrays.sort(nums); subsetsWithDup(nums, 0, result, new LinkedList()); return result; } private void subsetsWithDup(int[] nums, int start, List> list, List path) { if (start == nums.length) { list.add(new LinkedList(path)); return; } path.add(nums[start]); subsetsWithDup(nums, start + 1, list, path); path.remove(path.size() - 1); // 既然不带当前字符，那后面如果重复的都别带，否则就是带了当前字符的子集 for ( ; start + 1 < nums.length && nums[start + 1] == nums[start]; start++); subsetsWithDup(nums, start + 1, list, path); } }