LeetCode90 Subsets II

问题来源LeetCode90

问题描述

Given a collection of integers that might contain duplicates, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,2], a solution is:

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

问题分析

这道题是LeetCode78 SubSets的延续，不过是多了一个有重复元素。一般对于有重复的元素的问题，可以考虑对数组进行排序，然后跳过重复的元素，这道题可以很简单的用这种方式进行解决。

代码如下

public List<List<Integer>> subsetsWithDup(int[] nums) {    result.add(new ArrayList<>());    if(nums==null||nums.length<1){        return  result;    }    //对数组进行排序    Arrays.sort(nums);    help(new ArrayList<>(),0,0,nums);    return result;}List<List<Integer>> result = new ArrayList<>();private void help(List<Integer> list,int from,int l,int[] nums){    if(l==nums.length){        return;    }else {        for (int i = from; i < nums.length; i++) {            if(i>from && nums[i]==nums[i-1]){                //重复的元素，跳过                continue;            }            list.add(nums[i]);            result.add(new ArrayList<>(list));            help(list,i+1,l+1,nums);            list.remove(list.size()-1);        }    }}

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GitHub地址 https://github.com/yanqinghe/leetcode

CSDN博客地址 http://blog.csdn.net/yanqinghe123/article/category/7176678