Module aoc::year2023::day10

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§Pipe Maze

This solution uses the Shoelace formula and Pick’s theorem.

Starting at S we trace out the path followed by the pipes. Each corner piece (7, F, J, L and finally S) is considered a vertex and added to the running total for the area using the Shoelace formula. Additionally we keep track of the perimeter length.

As the path is a loop the answer for part one is half the perimeter length.

The answer for part two is the number of interior points. Rearranging Pick’s theorem:

A = i + b / 2 - 1 => i = A - b / 2 + 1

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