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Day 23 brute force solution that takes over an hour for p2

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Chris Pickett
2020-12-23 17:16:19 -06:00
parent 0a3fe365d0
commit 29ee7eee26
4 changed files with 149 additions and 0 deletions
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3
2020.csproj
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@ -71,6 +71,9 @@
<None Update="22input.txt">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</None>
<None Update="23input.txt">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</None>
</ItemGroup>
</Project>

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23input.txt Normal file
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538914762

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Program.cs
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@ -25,6 +25,7 @@
Q20.Go();
Q21.Go();
Q22.Go();
Q23.Go();
Util.Log($"Total time={(System.DateTime.Now - start).TotalMilliseconds}ms");
}
}

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Q23.cs Normal file
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using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace _2020
{
class Q23
{
static readonly List<int> list = new List<int>();
public static void Go()
{
var start = DateTime.Now;
MakeList();
Util.Log($"Q23 MakeList took {(DateTime.Now - start).TotalMilliseconds}ms");
var p1start = DateTime.Now;
Part1();
Util.Log($"Q23 part1 took {(DateTime.Now - p1start).TotalMilliseconds}ms");
var p2start = DateTime.Now;
Part2();
Util.Log($"Q23 part2 took {(DateTime.Now - p2start).TotalMilliseconds}ms");
Util.Log($"Q23 took {(DateTime.Now - start).TotalMilliseconds}ms");
}
static void MakeList()
{
var text = File.ReadAllText("23input.txt");
foreach (var ch in text)
{
list.Add(Convert.ToInt32(ch.ToString()));
}
}
static int mod(int x, int m)
{
int r = x;
if (r >= x)
{
r = x % m;
}
return r < 0 ? r + m : r;
}
static void Part1()
{
var cupList = new List<int>(list);
var currentCupVal = cupList[0];
var currentCupIdx = 0;
var pickedUp = new int[3];
for (int move = 0; move < 100; move++)
{
for (int i = currentCupIdx + 1, pickedUpIdx = 0; pickedUpIdx < 3; pickedUpIdx++)
{
if (i >= cupList.Count)
{
i = 0;
}
pickedUp[pickedUpIdx] = cupList[i];
cupList.RemoveAt(i);
}
var destCupVal = currentCupVal - 1;
var destCupIdx = cupList.IndexOf(destCupVal);
while (destCupIdx < 0)
{
destCupVal = mod(destCupVal - 1, cupList.Count + pickedUp.Length + 1);
destCupIdx = cupList.IndexOf(destCupVal);
}
cupList.InsertRange(destCupIdx + 1, pickedUp);
currentCupVal = cupList[mod(cupList.IndexOf(currentCupVal) + 1, cupList.Count)];
currentCupIdx = cupList.IndexOf(currentCupVal);
}
var startIdx = cupList.IndexOf(1);
var scoreStr = "";
for (var idx = startIdx + 1; scoreStr.Length < cupList.Count - 1; idx++)
{
scoreStr += cupList[idx % cupList.Count].ToString();
}
Util.Log($"Q23Part1: labels={scoreStr}");
}
static void Part2()
{
var cupList = new List<int>(list);
var highestVal = cupList.Aggregate(0, (result, curr) => curr > result ? curr : result);
for (int i = cupList.Count, next = highestVal + 1; i < 1000000; i++, next++)
{
cupList.Add(next);
}
var currentCupVal = cupList[0];
var currentCupIdx = 0;
var pickedUp = new int[3];
var start = DateTime.Now;
var lastMove = 0;
for (int move = 0; move < 10000000; move++)
{
for (int i = currentCupIdx + 1, pickedUpIdx = 0; pickedUpIdx < 3; pickedUpIdx++)
{
if (i >= cupList.Count)
{
i = 0;
}
pickedUp[pickedUpIdx] = cupList[i];
cupList.RemoveAt(i);
}
var destCupVal = currentCupVal - 1;
var destCupIdx = cupList.IndexOf(destCupVal);
while (destCupIdx < 0)
{
destCupVal = mod(destCupVal - 1, cupList.Count + pickedUp.Length + 1);
destCupIdx = cupList.IndexOf(destCupVal);
}
cupList.InsertRange(destCupIdx + 1, pickedUp);
currentCupVal = cupList[mod(cupList.IndexOf(currentCupVal) + 1, cupList.Count)];
currentCupIdx = cupList.IndexOf(currentCupVal);
var dt = DateTime.Now - start;
var dtSeconds = dt.TotalSeconds;
if (dtSeconds >= 1.0)
{
start = DateTime.Now;
var rate = (move - lastMove) / dtSeconds;
lastMove = move;
var remainingMoves = 10000000 - move;
var endTime = DateTime.Now + TimeSpan.FromSeconds(remainingMoves / rate);
Util.Log($"Current rate: {rate:N1} mps, {remainingMoves:N} moves remaining. Should be done by {endTime}");
}
}
var oneIdx = cupList.IndexOf(1);
Util.Log($"Q23Part2: next two={cupList[(oneIdx + 1) % cupList.Count]}, {cupList[(oneIdx + 2) % cupList.Count]}, multiplied={1L * cupList[(oneIdx + 1) % cupList.Count] * cupList[(oneIdx + 2) % cupList.Count]}");
}
}
}