[LeetCode] 228. Summary Ranges

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

For number A,  create the initial range [A, A].  If the next number B = A + 1, then extends the range as [A, B]. Otherwise create new initial range [B, B] and append to the result list.

Time Complexity = O ( N )

Space Complexity = O ( N )

class Solution:
    def summaryRanges(self, nums: List[int]) -> List[str]:
        result = []
        
        for n in nums:
            if result and n == result[-1][1] + 1:
                result[-1][1] = n
            else:
                result.append([n, n])
        
        return ["{}->{}".format(a, b) if a != b else "{}".format(a) for a, b in result]