题目： 给定一个无重复元素的有序整数数组，返回数组区间范围的汇总。 思路： 本题思路简单。 程序： class Solution:     def summaryRanges(self, nums: List[int]) -> List[str]:         length = len(nums)         if length <= 0:             return []         if length == 1:             return [str(nums[0])]         result = []         head = 0         for index in range(1, length):             if nums[index] - nums[index - 1] != 1:                 tail = index - 1                 if head == tail:                     result.append(str(nums[head]))                 else:                     result.append(str(nums[head]) + '->' + str(nums[tail]))                 if index != length - 1:                     head = index                 else:                     result.append(str(nums[length - 1]))             elif nums[index] - nums[index - 1] == 1 and index == length - 1:                 result.append(str(nums[head]) + '->' + str(nums[index]))         return result