228.Summary Ranges

Tags: [string], [two_pointer]

Com: {g}

Link: https://leetcode.com/problems/summary-ranges/\#/description

Given a sorted integer array without duplicates, return the summary of its ranges.

For example, given[0,1,2,4,5,7], return["0->2","4->5","7"].

Solution: Two Pointer

class Solution(object):
    def summaryRanges(self, nums):
        """
        :type nums: List[int]
        :rtype: List[str]
        """
        if not nums or len(nums) <= 1:
            return [str(x) for x in nums]

        size = len(nums)
        result = []
        start = 0
        end = 1
        while end < size:
            if nums[end - 1] + 1 < nums[end]:
                if start == end - 1:
                    result.append(str(nums[start]))
                else:
                    result.append('{}->{}'.format(nums[start], nums[end - 1]))

                start = end

            end += 1

        if start == end - 1:
            result.append(str(nums[start]))
        else:
            result.append('{}->{}'.format(nums[start], nums[end - 1]))

        return result

Note:

• Time complexity = O(n), n is the length of the given string.