class Solution:
    def summaryRanges(self, nums: List[int]) -> List[str]:
        if not nums:
            return nums

        ans = []
        tmp_ans = []
        idx = 0
        while(idx < len(nums)):
            tmp_ans.append(nums[idx])
            while idx+1 < len(nums) and nums[idx+1] == nums[idx] + 1:
                idx += 1
                tmp_ans.append(nums[idx])
            else:
                if len(tmp_ans) > 1:
                    s = f"{tmp_ans[0]}->{tmp_ans[-1]}"
                else:
                    s = f"{tmp_ans[0]}"
            ans.append(s)
            idx += 1
            tmp_ans = []
        return ans