[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:    vector<vector<int> >ans;    set<vector<int> > res;    vector<int> v;    vector<vector<int> > combinationSum2(vector<int> &candidates, int target) {        sort(candidates.begin(),candidates.end());        generate(candidates,0,0,target);        for(set<vector<int> >::iterator it = res.begin();it != res.end();it ++)            ans.push_back(*it);        return ans;    }    void generate(vector<int> cand,int sum,int start,int target){        if(sum == target){            res.insert(v);            return;        }        for(int i = start;i < cand.size();++ i){            v.push_back(cand[i]);            sum += cand[i];            if(sum > target){                v.pop_back();                break;            }            generate(cand,sum,i + 1,target);            v.pop_back();            sum -= cand[i];        }    }};