[LeetCode] Combination Sum II

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:

    void getComb(vector<vector<int>> &result, vector<int> &num, vector<int> solution, int target, int start)
    {
        if(target==0)
        {
            result.push_back(solution);
            return;
        }
        if(target < 0)
            return;
            
        for(int i=start;i<num.size();i++)
        {
            solution.push_back(num[i]);
            int nexttarget=target - num[i];
            getComb(result,num,solution,nexttarget,i+1);
            solution.pop_back();
            while(i<num.size() && num[i]==num[i+1]) //num=[1,1], target=1, avoid result=[[1],[1]]
                i++;
        }
    }

    vector<vector<int> > combinationSum2(vector<int> &num, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(num.begin(),num.end());
        vector<vector<int>> result;
        vector<int> solution;
        int start=0;
        if(target==0)
            return result;
            
        getComb(result,num,solution,target,start);
        
        return result;
    }
};