Distinct Date I

Finding dates with all distinct digits

This is a medium-difficulty puzzle that tests your ability to reason about constraints and systematically search a large space. It's the kind of problem quant interview loops use to see whether you can break down a concrete specification into logic, then implement or reason through it efficiently.

The core challenge is understanding what "distinct digits" means across a full date representation, then either searching forward from a given point or reasoning about which date ranges satisfy the constraint. A strong approach identifies which digit combinations are impossible (for instance, a date cannot repeat any of the 10 digits 0–9), narrows the search space, and avoids checking every single date manually.

• Constraint satisfaction and search pruning
• Date validity and calendar arithmetic
• Digit enumeration and overlap detection