class Solution:
    def summaryRanges(self, nums: List[int]) -> List[str]:
        left, right = 0,0
        size = len(nums)
        res = []
        while left < size and right < size:
            if right == size -1 or nums[right+1] != nums[right]+1 :
                if left == right:
                    res.append(f"{nums[left]}")
                else:
                    res.append(f"{nums[left]}->{nums[right]}")
                left = right + 1
                right = left
            else: 
                right = right + 1
        return res
        

class Solution:
    def combine(self, n: int, k: int) -> List[List[int]]:
        res = []
        def dfs(path: List[int],x:int) :
            if len(path) == k: 
                res.append(path)
                return 
            else:
                for i in range(x,n+1):
                    path.append(i)
                    dfs(path, i+1)
                    path.pop()
        s = []
        dfs(path, 1)
        return res