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Advent of Code 2015 Day 18: https://adventofcode.com/2015/day/18
A relatively easy challenge, we essentially keep track of all of the lights
as points on a grid (std::collections::HashMap) and then for each step
evaluate the neighbors to build a new grid and then replace the current
grid with the new grid in order to make one atomic option. Lights on the
edge should have their neighbors considered off which is easy with the
HashMap lookup: if we don’t have a neighbor because it doesn’t exist in the
grid then don’t increment the turned-on-neighbor count. In part two we
just continually always set the corners to on.
Functions§
- The solution for the day eighteen challenge.