Distinct Date II

What this date-logic puzzle tests

This is a medium-difficulty puzzle that combines constraint reasoning with systematic search. It asks you to find a calendar date meeting a specific digit property, then express it in a prescribed format. The challenge is not computational intensity, but rather clear thinking about how to frame the search space and verify your answer against the constraint.

To approach problems like this, candidates typically work backwards from the present or scan through valid dates mentally, checking whether each candidate satisfies the uniqueness condition. The problem rewards logical structuring: understanding what makes a date valid on the calendar, which digit positions matter, and how to avoid false candidates. It also tests attention to detail in interpreting the output format and the date format specified in the prompt.

• Constraint satisfaction and systematic enumeration
• Calendar arithmetic and date validity
• Set reasoning (distinct elements)
• Format conversion and careful reading