[Python] 순열 조합 구현

순열

def permute(self, nums: List[int]) -> List[List[int]]:
        answer = []
        prev_elements = []
        
        def dfs(elements):
            if len(elements) == 0:
                answer.append(prev_elements[:])
                return
            
            for e in elements:
                next_elements = elements[:]
                next_elements.remove(e)
                
                prev_elements.append(e)
                dfs(next_elements)
                prev_elements.pop()
        dfs(nums)        
        return answer

 

 

조합

def combine(self, n: int, k: int) -> List[List[int]]:
        answer = []
        num_list = [i for i in range(1, n+1)]
        def dfs(elements, start, target):
            if target == 0 :
                answer.append(elements[:])
                return
            
            for i in range(start, len(num_list)):
                elements.append(num_list[i])
                dfs(elements, i+1, target - 1)
                elements.pop()
        dfs([], 0, k)
        return answer