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3.4x speedup on Day 12

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First round of the lowest of low-hanging fruits to get day 12 runtime from ~1s to ~280ms on my machine in Release. Still not happy with 280ms, so I will probably keep digging.
This commit is contained in:
Chris Pickett
2021-12-12 10:57:29 -06:00
parent 0dc2abeca9
commit c292bd45c6
1 changed files with 14 additions and 12 deletions
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22
src/12.cs
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@ -20,9 +20,15 @@ internal class Day12
paths[points[1]] = new List<string>(); paths[points[1]] = new List<string>();
} }
if (points[0] != "end" && points[1] != "start")
{
paths[points[0]].Add(points[1]); paths[points[0]].Add(points[1]);
}
if (points[1] != "end" && points[0] != "start")
{
paths[points[1]].Add(points[0]); paths[points[1]].Add(points[0]);
} }
}
Part1(paths); Part1(paths);
Part2(paths); Part2(paths);
Logger.Log(""); Logger.Log("");
@ -38,28 +44,24 @@ internal class Day12
Logger.Log($"part1: {validPaths.Count}"); Logger.Log($"part1: {validPaths.Count}");
} }
private static void FindPaths(Dictionary<string, List<string>> paths, List<List<string>> routes, List<string> currRoute, bool canVisitSmallCaveTwice) private static void FindPaths(Dictionary<string, List<string>> paths, List<List<string>> routes, List<string> currRoute, bool canVisitSmallCaveTwice, bool hasDoubledCave = false)
{ {
//Logger.Log($"Current path: {string.Join(',', currRoute)}"); //Logger.Log($"Current path: {string.Join(',', currRoute)}");
var curr = currRoute.Last(); var curr = currRoute.Last();
foreach (var next in paths[curr]) foreach (var next in paths[curr])
{ {
//Logger.Log($" Evaluating next: {next}"); //Logger.Log($" Evaluating next: {next}");
if (next == "start")
{
//Logger.Log($" is start, skipping");
continue;
}
if (next != "end" && next.ToLower() == next && currRoute.Contains(next)) if (next != "end" && next.ToLower() == next && currRoute.Contains(next))
{ {
if (!canVisitSmallCaveTwice) if (!canVisitSmallCaveTwice || hasDoubledCave)
{ {
//Logger.Log($" is already-visited small cave, skipping"); //Logger.Log($" is already-visited small cave, skipping");
continue; continue;
} }
else if (currRoute.Any(x => x.ToLower() == x && currRoute.Count(y => x == y) == 2)) else if (currRoute.Any(x => x[0] >= 'a' && x[0] <= 'z' && currRoute.Count(y => x == y) == 2))
{ {
//Logger.Log($" is already-visited small cave and we have already been to another one twice, skipping"); //Logger.Log($" is already-visited small cave and we have already been to another one twice, skipping");
hasDoubledCave = true;
continue; continue;
} }
} }
@ -68,11 +70,11 @@ internal class Day12
if (next == "end") if (next == "end")
{ {
//Logger.Log($" is end, so adding {string.Join(',', currRoute)} to valid paths"); //Logger.Log($" is end, so adding {string.Join(',', currRoute)} to valid paths");
routes.Add(currRoute); routes.Add(new List<string>(currRoute));
} }
else else
{ {
FindPaths(paths, routes, new List<string>(currRoute), canVisitSmallCaveTwice); FindPaths(paths, routes, currRoute, canVisitSmallCaveTwice, hasDoubledCave);
} }
currRoute.RemoveAt(currRoute.Count - 1); currRoute.RemoveAt(currRoute.Count - 1);