Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• Elements in a combination (a1, a2, … , ak) must be in non-descending order. (ie, a1 ≤ a2 ≤ … ≤ ak).
• The solution set must not contain duplicate combinations.

For example, given candidate set 10,1,2,7,6,1,5 and target 8, 
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

class Solution {
public:
    std::vector<std::vector<int> > combinationSum2(std::vector<int> &num, int target) {
		std::sort(num.begin(),num.end());
		dfs(num,0,target);
		return res;
    }
private:
	std::vector<int> path;
	std::vector<std::vector<int>> res;
	void dfs(std::vector<int> &num, int start, int target)
	{
		if(target == 0)
		{
			res.push_back(path);
			return;
		}
		else
		{
			for (int i = start; i < num.size(); i++)
			{
				if(i != start && num[i-1] == num[i])
				{
					continue;
				}
				if(target >= num[i])
				{
					path.push_back(num[i]);
					dfs(num,i+1,target-num[i]);
					path.pop_back();
				}
			}
		}
	}
};

leetcode - Combination Sum II