题解 | #牛群分组II#

class Solution {
public:
    vector<int> path;
    vector<vector<int> > res;
    bool is_equal(vector<int> &arr, int target)
    {
        int sum = 0;
        for (int i = 0;i < arr.size();i++) {
            sum += arr[i];
        }
        return sum == target;
    }

    void backtracking(vector<int> &candidates, int start_index, int target)
    {
        if (is_equal(path, target)) {
            res.push_back(path);
            return;
        }
        for (int i = start_index; i < candidates.size();i++) {
            path.push_back(candidates[i]);
            backtracking(candidates, i + 1, target);
            path.pop_back();
        }
    }
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param candidates int整型vector 
     * @param target int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > cowCombinationSum2(vector<int>& candidates, int target) {
        // write code here
        backtracking(candidates, 0, target);
        return res;
        
    }
};