Combination Sum II

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

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

Note:

All numbers (including target) will be positive integers. The solution set must not contain duplicate combinations. Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8, A solution set is: [ [1, 7], [1, 2, 5], [2, 6], [1, 1, 6] ]

Example 2:

Input: candidates = [2,5,2,1,2], target = 5, A solution set is: [ [1,2,2], [5] ]

Solution:

    void combinationSum2Util(vector<int>& candidates, int target, int start, vector<int> &sol, vector<vector<int>> &ans) {
        if (target == 0) {
            ans.push_back(sol);
        } else if (target > 0) {
            for (int i=start; i<candidates.size(); i++) {
                if (i > start && candidates[i] == candidates[i - 1]) continue;
                sol.push_back(candidates[i]);
                combinationSum2Util(candidates, target-candidates[i], i+1, sol, ans);
                sol.pop_back();
            }
        }

        return;
    }

    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<int> sol;
        vector<vector<int>> ans;
        sort(candidates.begin(), candidates.end());
        combinationSum2Util(candidates, target, 0, sol, ans);
        return ans;
    }