cpp-flashcards/org/study_deck_02/dsa/backtracking/0077-combinations.org

#+ANKI_DECK: study_deck_02
* TODO 0077. Combinations :medium:
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*0077. Combinations][0077. Combinations]]
:END:

Given two integers ~n~ and ~k~, return /all possible combinations of/ ~k~ /numbers chosen from the range/ ~[1, n]~.

You may return the answer in *any order*.

*Example 1:*


#+begin_src
Input: n = 4, k = 2
Output: [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
Explanation: There are 4 choose 2 = 6 total combinations.
Note that combinations are unordered, i.e., [1,2] and [2,1] are considered to be the same combination.
#+end_src


*Example 2:*


#+begin_src
Input: n = 1, k = 1
Output: [[1]]
Explanation: There is 1 choose 1 = 1 total combination.
#+end_src


*Constraints:*

 - ~1 <= n <= 20~

 - ~1 <= k <= n~

** TODO Approach
Write your approach here.

** TODO Python
#+begin_src python :lc-problem 77 :lc-lang python3
class Solution:
    def combine(self, n: int, k: int) -> List[List[int]]:
#+end_src

** TODO C++
#+begin_src cpp :lc-problem 77
class Solution {
public:
    vector<vector<int>> combine(int n, int k) {
        
    }
};
#+end_src