LeetCode OJ:Combination Sum II

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 {
    vector<vector<int> > result; 
    vector<int> res; 
public:
    void dfs(vector<int>& candidates, int target, int start) {
        if (target <= 0) {
            if(target == 0){
                result.push_back(res);
            }
            return;
        }
        for (int i = start; i < candidates.size(); i++) {
            res.push_back(candidates[i]); 
            dfs(candidates, target - candidates[i], i+1);
            res.pop_back();
            while(i<candidates.size()-1 && candidates[i]==candidates[i+1])i++;  
        }
    }
    vector<vector<int> > combinationSum2(vector<int> &num, int target) {
        sort(num.begin(), num.end());
        dfs(num, target, 0);
        return result;
    }
};