文章作者：Tyan 部落格：noahsnail.com  |  CSDN  |  簡書

1. Description

2. Solution

• Version 1

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        set<vector<int>> s;
        sort(candidates.begin(), candidates.end());
        vector<int> combination;
        combinationSum2(s, candidates, combination, target, 0, 0);
        return vector<vector<int>>(s.begin(), s.end());
    }


private:
    void combinationSum2(set<vector<int>>& result, vector<int>& candidates, vector<int>& combination, int& target, int sum, int begin) {
        if(sum > target) {
            return;
        }
        if(sum == target) {
            result.insert(combination);
            return;
        }
        for(int i = begin; i < candidates.size(); i++) {
            combination.push_back(candidates[i]);
            combinationSum2(result, candidates, combination, target, sum + candidates[i], i + 1);
            combination.pop_back();
        }
    }
};
 

• Version 2

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        set<vector<int>> s;
        sort(candidates.begin(), candidates.end());
        vector<int> combination;
        combinationSum2(s, candidates, combination, target, 0, 0);
        return vector<vector<int>>(s.begin(), s.end());
    }


private:
    void combinationSum2(set<vector<int>>& result, vector<int>& candidates, vector<int>& combination, int& target, int sum, int begin) {
        if(sum > target) {
            return;
        }
        if(sum == target) {
            result.insert(combination);
            return;
        }
        for(int i = begin; i < candidates.size(); i++) {
            if(sum + candidates[i] > target) {
                break;
            }
            combination.push_back(candidates[i]);
            combinationSum2(result, candidates, combination, target, sum + candidates[i], i + 1);
            combination.pop_back();
        }
    }
};
 

• Version 3

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<vector<int>> result;
        sort(candidates.begin(), candidates.end());
        vector<int> combination;
        combinationSum2(result, candidates, combination, target, 0, 0);
        return result;
    }


private:
    void combinationSum2(vector<vector<int>>& result, vector<int>& candidates, vector<int>& combination, int& target, int sum, int begin) {
        if(sum > target) {
            return;
        }
        if(sum == target) {
            result.push_back(combination);
            return;
        }
        for(int i = begin; i < candidates.size(); i++) {
            if(sum + candidates[i] > target) {
                break;
            }
            if(i > begin && candidates[i] == candidates[i - 1]) {
                continue;
            }
            combination.push_back(candidates[i]);
            combinationSum2(result, candidates, combination, target, sum + candidates[i], i + 1);
            combination.pop_back();
        }
    }
};
 

Reference