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Shave a few ms off day 14

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This is a small low-hanging fruit pass. I was really just curious where the time was going since I didn't feel like the algorithm was actually expensive. Turns out it's not, really...the larger cost is setting up the frequencies and pairs collections, and computing min/max was 9x more expensive than it needed to be (I was expecting 2x since I was iterating over the collection twice, but 9x is...unreasonable, so I just unrolled it myself). It also turns out that MinBy() is marginally slower than Min() with no gain (for this use case), so that was an easy win on the brute force solution.
This commit is contained in:
Chris Pickett
2021-12-14 12:51:50 -06:00
parent 07cad08733
commit aaf31ed7b1
1 changed files with 30 additions and 24 deletions
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54
src/14.cs
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@ -33,6 +33,13 @@ internal class Day14 : Day
string curr = template;
Dictionary<char, int> frequencies = new();
foreach (var pair in rules)
{
frequencies[pair.Key[0]] = 0;
frequencies[pair.Key[1]] = 0;
}
for (int i = 0; i < 10; i++)
{
StringBuilder sb = new();
@ -41,24 +48,18 @@ internal class Day14 : Day
sb.Append(curr[j]);
sb.Append(rules[curr[j..(j + 2)]]);
}
sb.Append(curr[curr.Length - 1]);
sb.Append(curr[^1]);
curr = sb.ToString();
}
Dictionary<char, int> frequency = new();
foreach (var c in curr)
{
if (!frequency.ContainsKey(c))
{
frequency.Add(c, 0);
}
frequency[c]++;
frequencies[c]++;
}
var least = frequency.MinBy(x => x.Value);
var most = frequency.MaxBy(x => x.Value);
var least = frequencies.Min(x => x.Value);
var most = frequencies.Max(x => x.Value);
Logger.Log($"part1: <blue>{most.Value - least.Value}<r>");
Logger.Log($"part1: <blue>{most - least}<r>");
}
private static void Part2(string template, Dictionary<string, char> rules)
@ -69,15 +70,9 @@ internal class Day14 : Day
Dictionary<char, long> frequencies = new();
foreach (var pair in rules)
{
pairs.Add(pair.Key, 0);
if (!frequencies.ContainsKey(pair.Key[0]))
{
frequencies.Add(pair.Key[0], 0);
}
if (!frequencies.ContainsKey(pair.Key[1]))
{
frequencies.Add(pair.Key[1], 0);
}
pairs[pair.Key] = 0;
frequencies[pair.Key[0]] = 0;
frequencies[pair.Key[1]] = 0;
}
for (int i = 0; i < template.Length - 1; i++)
{
@ -89,7 +84,7 @@ internal class Day14 : Day
for (int round = 0; round < 40; round++)
{
foreach (var pair in pairs.Where(x => x.Value > 0).ToList())
foreach (var pair in pairs.ToList())
{
pairs[pair.Key] -= pair.Value;
frequencies[rules[pair.Key]] += pair.Value;
@ -101,9 +96,20 @@ internal class Day14 : Day
}
}
var least = frequencies.MinBy(x => x.Value);
var most = frequencies.MaxBy(x => x.Value);
long least = long.MaxValue;
long most = long.MinValue;
foreach (var pair in frequencies)
{
if (pair.Value < least)
{
least = pair.Value;
}
if (pair.Value > most)
{
most = pair.Value;
}
}
Logger.Log($"part2: <blue>{most.Value - least.Value}<r>");
Logger.Log($"part2: <blue>{most - least}<r>");
}
}