228. Summary Ranges[M]

https://leetcode.com/problems/summary-ranges/

Description

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

Example 1:

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Input:  [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]
Explanation: 0,1,2 form a continuous range; 4,5 form a continuous range.

Example 2:

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Input:  [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]
Explanation: 2,3,4 form a continuous range; 8,9 form a continuous range.

Solution

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class Solution:
    def summaryRanges(self, nums: List[int]) -> List[str]:
        res = []
        start, ls = 0, len(nums)
        for i in range(ls):
            if i + 1 <  ls and nums[i + 1] == nums[i] + 1:
                continue
            if i == start:
                res.append(str(nums[start]))
            else:
                res.append("%d->%d" % (nums[start], nums[i]))
            start = i + 1
        return res