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>> ans;
    void recursive(int start, int n, vector<int> path, int depth, int k) {
        if (depth == k) {
            ans.push_back(path);
            return;
        }
        for (int i = start+1; i < n; i++) {
            path.push_back(i+1);
            recursive(i, n, path, depth+1, k);
            path.pop_back();
        }
    }

    vector<vector<int> > combine(int n, int k) {
        // write code here
        for (int i = 0; i < n; i++) {
            vector<int> path;
            path.push_back(i+1);        
            recursive(i, n, path, 1, k);
        }
        return ans;
    }
};