Combinations Recursive

combinations_recursive.py

class Solution:
    
    def combine(self, n: int, k: int) -> List[List[int]]:
        nums = list(range(1, n + 1))
        combinations = []
        
        def combine_helper(ans: List[int], path: List[int], options: List[int], count: int):
            if count == 0:
                ans.append(path)
            else:
                for index, num in enumerate(options):
                    combine_helper(ans, path+[num], options[index + 1:], count - 1)
                
        combine_helper(combinations, [], nums, k)
        
        return combinations