Problem 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.
Key Insights
- Sequential digits can only be formed using the digits from 1 to 9.
- The maximum number of sequential digits is limited due to the digits being consecutive.
- We can generate all possible sequential digit numbers and then filter them based on the provided range [low, high].
- The generation can be done using a simple loop that builds numbers with increasing digits.
Space and Time Complexity
Time Complexity: O(1) - The number of sequential digits is small (at most 36). Space Complexity: O(1) - We are using a fixed amount of space to store the results.
Solution
To solve the problem, we will generate all possible sequential digit numbers from 1 to 9. We can start from each digit and build the number by appending the next consecutive digit. We will store these numbers in a list, and after generating them, we will filter this list to include only numbers within the range [low, high]. Finally, we will sort the resulting list before returning it.