题解 | #牛棚分组#

class Solution {
public:
    /**
     * 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 n int整型 
     * @param k int整型 
     * @return int整型vector<vector<>>
     */
vector<vector<int>> res;
    vector<int> path;
 
    void backtracking(int n, int k, int index) {
        if (path.size() == k) {
            res.push_back(path);
            return;
        }
        for (int i = index; i < n - (path.size() - k); i++) {
            path.push_back(i);
            backtracking(n, k, i + 1);
            path.pop_back();
        }
    }
 
    vector<vector<int> > combine(int n, int k) {
        // write code here
        backtracking(n, k, 1);
        return res;
    }
};