private static void AddDeadEnd(List <StringBuilder> triedTheseChains, AdapterChain testChain)
{
triedTheseChains.Add(new StringBuilder());
var idx = triedTheseChains.Count - 1;
for (int i = 0; i < testChain.Chain.Count; i++)
{
triedTheseChains[idx].Append(testChain.Chain[i].ToString());
}
return;
}
private static void PrintChainToConsole(AdapterChain candidateChain)
{
Console.WriteLine($"Item count: {candidateChain.Chain.Count}");
// print chain
for (int i = 0; i < candidateChain.Chain.Count; i++)
{
if (i < candidateChain.Chain.Count - 1)
{
Console.Write($"{candidateChain.Chain[i]},");
}
else
{
Console.WriteLine($"{candidateChain.Chain[i]}");
}
}
}
private static void FindDistribution(AdapterChain candidateChain)
{
Dictionary <int, int> dist = new Dictionary <int, int> {
{ 1, 0 }, { 2, 0 }, { 3, 0 }
};
var d = 0;
var c = 0; // for debug count items incl in distro should equal #items in chain-1 + 1 additional item the device itself
// for each item find joltage diff between it and its previous item
for (int i = 1; i < candidateChain.Chain.Count; i++)
{
c += 1;
d = candidateChain.Chain[i] - candidateChain.Chain[i - 1];
if (d > 3 || d < 1)
{
Console.WriteLine("Error");
}
else
{
dist[d] = dist[d] + 1;
}
}
c += 1;
dist[3] = dist[3] + 1; // add diff between device and last adapter in the chain. it's always +3
//print joltage distro
foreach (KeyValuePair <int, int> entry in dist)
{
Console.WriteLine($"{entry.Key.ToString()}, diff {entry.Value.ToString()}");
}
// print product of +1 count by +3 count
Console.WriteLine($"Product of +1 count x +3 count is {dist[1]} * {dist[3]} = {dist[1]*dist[3]}. Items in distro is {c}");
return;
}
static void Main(string[] args)
{
// Advent of Code 2020 Day 10 Puzzle Adapter Array https://adventofcode.com
// 12/10/2020
Console.WriteLine(@"--- Day 10: Adapter Array ---");
var rf = new ReadPuzzleInputFile();
var adapters = rf.ReadFile();
// adapters is a list of integers. Each integer represents an adapter's jolts.
//No other info is provided and adapters are known only by their postion or index in this list.
Console.WriteLine($"Read input file. {rf.LinesRead} lines read in.");
AdapterChain candidateChain;
List <StringBuilder> deadEndChains = new List <StringBuilder>();
adapters.Sort(); // sort the adapter list ascending
// algorithm: Brute Force!
// check everything and build up a list of valid chains until we find a complete chain from wall to device.
candidateChain = new AdapterChain();
candidateChain.Chain.Add(0); // always start at 0
bool testComplete = false;
int thisAdapter = 0; // start at the wall always, add index of this adapter in list of adapters
bool foundChain = false;
List <int> next3;
// build a chain one element at a time
do
{
thisAdapter += 1;
next3 = FindNext3(adapters, thisAdapter); // List<int> with 0 to 3
next3.Sort();
// try to add another item
var fail = false; //optimistic
if (next3.Count > 0)
{
var addThisItem = 0;
int i;
for (i = 0; i < next3.Count; i++)
{
var tmpChain = new List <int>();
for (int j = 0; j < candidateChain.Chain.Count; j++)
{
tmpChain.Add(candidateChain.Chain[j]);
}
tmpChain.Add(next3[i]);
if (IsThisANewChain(deadEndChains, tmpChain))
{
addThisItem = i;
break;
}
}
if (i < next3.Count)
{
candidateChain.Chain.Add(next3[addThisItem]);
}
else
{
fail = true;
}
}
if (fail)
{
// add this test case to list of those tried.
AddDeadEnd(deadEndChains, candidateChain);
testComplete = true;
}
} while (!testComplete && thisAdapter < adapters.Count);
if (candidateChain.Chain.Count == adapters.Count + 1) // candidate chain will include wall +1 for items count.
{
foundChain = true;
}
if (foundChain)
{
Console.WriteLine($"Found chain");
PrintChainToConsole(candidateChain);
FindDistribution(candidateChain);
}
else
{
Console.WriteLine($"Did not find chain");
}
///////////////////////////////////////////////
// part 2: how many valid combos are there?
Console.WriteLine($"\nPart 2.");
// In part 2 adapters can be skipped over and not used. Goal is count total number of combos instead of using all the adapters.
// algorthm: at each node in the chain there are only so many valid adapters to choose from.
// record how many are available.
adapters.Sort(); // sort the adapter list ascending
// when a complete set of pathways from an adapter to end of list is found keep track of it here
Dictionary <int, double> completePathsCount = new Dictionary <int, double>();
// start with highest rated item.
// +1 for highest rated item.
Accumulator count = new Accumulator();
Accumulator recursionCount = new Accumulator();
adapters.Insert(0, 0); // add the wall outlet
count.AddDataValue(FindPaths(adapters, 0, completePathsCount, recursionCount));
if (count.Total != 0)
{
Console.WriteLine($"Count of valid adapter combos is {count.Total}");
Console.WriteLine($"Count of recursive calls to find all paths is {recursionCount.Total}");
}
else
{
Console.WriteLine($"Count of valid adapter combos is 0 - no valid path thru this list. ???");
}
Console.WriteLine("Done.");
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}