leetcode-228-汇总区间

题目描述：

 

 

 第一次提交：双指针 O(N)

class Solution:
    def summaryRanges(self, nums: List[int]) -> List[str]:
        #first = 0
        last = 0
        res = []
        while last!=len(nums):
            first = last
            while last+1<len(nums) and nums[last+1]-nums[last]==1:
                last += 1
            if first == last:
                res.append(str(nums[first]))
            else:
                res.append("{}->{}".format(nums[first],nums[last]))
            last += 1
        return res