1291. Sequential Digits

Problem

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 (Java)

class Solution {
    public List<Integer> sequentialDigits(int low, int high) {
        int[] arr = {
            12, 23, 34, 45, 56, 67, 78, 89, 123, 234, 345, 456, 567, 678, 789, 1234, 2345, 3456,
            4567, 5678, 6789, 12345, 23456, 34567, 45678, 56789, 123456, 234567, 345678, 456789,
            1234567, 2345678, 3456789, 12345678, 23456789, 123456789
        };
        List<Integer> result = new ArrayList<>();
        for (int j : arr) {
            // 234    148         234        256
            if (j >= low && j <= high) {
                result.add(j);
            }
        }
        return result;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).