Strictly Climbing Digits

Difficulty: 1500 4000 ms 128 MB

digit-dp

Count the integers in [L, R] whose digits are strictly increasing left to right (like 1479).

Input: one line with two integers L and R.

Output: the count of qualifying integers in [L, R].

Constraints:

• 1 ≤ L ≤ R ≤ 10¹⁸

Sample Tests

1 30

24

100 200

28

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