1291-sequential-digits

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Description

An integer has sequential digits if and only if each digit in the number is one more than the previous digit.

Return a sorted list of all the integers in the range [low, high] inclusive that have sequential digits.

 

Example 1:

Input: low = 100, high = 300
Output: [123,234]

Example 2:

Input: low = 1000, high = 13000
Output: [1234,2345,3456,4567,5678,6789,12345]

 

Constraints:

• 10 <= low <= high <= 10^9

Solution(Python)

class Solution:
    #     def isSequential(self,num):
    #         candidate = num
    #         candidate,after = divmod(candidate,10)

    #         while  candidate > 0:
    #             candidate,before = divmod(candidate,10)

    #             if after != before+1:
    #                 return False
    #             after = before
    #         return True

    #     def sequentialDigits(self, low: int, high: int) -> List[int]:
    #         res = []

    #         for num in range(low,high):
    #             if self.isSequential(num):
    #                 res.append(num)

    #         return res
    # Time Complexity: O(M-N)

    def sequentialDigits(self, low, high):
        out = []
        string = "123456789"

        for i in range(len(str(low)), len(str(high)) + 1):
            for j in range(10 - i):
                num = int(string[j: j + i])
                if low <= num and num <= high:
                    out.append(num)

        return out


# Time Complexity: O(1)
# Space Complexity: O(1)