Module day23

Crab Cups

The cups form a singly linked list.

For performance instead of using pointers, we store the cups in a vec where an element at index i stores the index of the next cup. For example cup[1] points to the first cup after cup one and cup[cup[1]] points to second cup after cup one.

Notes:

• One million is approximately 2²⁰ so the closest integer size that fits is u32. Using u32 instead of usize increases speed due to better cache locality.
• Cups use one based indexing so the vec is one longer than the number of cups and the zeroth index is unused.

Functions

parse

part1

part2

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