LeetCode Subsets II

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Given a collection of integers that might contain duplicates, S, 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 S = [1,2,2], a solution is:

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

思路：再普通组合的情况下加上一个条件就是如果排序后数字重复的话，我们就只取第一个。

public class Solution {
    public List<List<Integer> > ans = new ArrayList<List<Integer> >();
	
	void dfs(int[] num, List<Integer> tmp, int cur) {
		List<Integer> t = new ArrayList<Integer>(tmp);
		ans.add(t);
		
		for (int i = cur; i < num.length; i++) {
			if (i != cur && num[i] == num[i-1]) continue;
			tmp.add(num[i]);
			dfs(num, tmp, i+1);
			tmp.remove(tmp.size()-1);
		}
	}
	
    public List<List<Integer> > subsetsWithDup(int[] num) {
    	Arrays.sort(num);
    	ans.clear();
    	List<Integer> tmp = new ArrayList<Integer>();
    	dfs(num, tmp, 0);
    	for (List<Integer> i : ans) 
    		System.out.println(i.toString());
    	return ans;
    }
}

LeetCode Subsets II

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原文地址：http://blog.csdn.net/u011345136/article/details/45049659