25 lines
857 B
Markdown
25 lines
857 B
Markdown
# Day4: Secure Container
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## Problem
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You arrive at the Venus fuel depot only to discover it's protected by a
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password. The Elves had written the password on a sticky note, but someone
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threw it out.
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However, they do remember a few key facts about the password:
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* It is a six-digit number.
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* The value is within the range given in your puzzle input.
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* Two adjacent digits are the same (like 22 in 122345).
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* Going from left to right, the digits never decrease; they only ever increase
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or stay the same (like 111123 or 135679).
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Other than the range rule, the following are true:
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* 111111 meets these criteria (double 11, never decreases).
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* 223450 does not meet these criteria (decreasing pair of digits 50).
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* 123789 does not meet these criteria (no double).
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How many different passwords within the range given in your puzzle input meet
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these criteria?
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