public static TallyOfResults Puzzle1(List <CircularArrayOfChar> map, int right, int down)
{
//current position
var x = 0; //horizontal
var y = 0; //vertical
var treeHits = 0;
var openHits = 0;
TallyOfResults r = new TallyOfResults();
x += right;
y += down;
while (y <= map.Count - 1)
{
if (map[y].GetValueAt(x) == tree)
{
treeHits += 1;
//System.Console.Write("hit ");
}
else
{
openHits += 1;
//System.Console.Write("mis ");
}
//System.Console.WriteLine($"{x},{y}"); // for debug
x += right;
y += down;
}
r.TreeHits = treeHits;
r.OpenSpaceHits = openHits;
r.ReachRight = x;
return(r);
}
static void Main(string[] args)
{
// Advent of Code 2020 Day 3 Puzzle https://adventofcode.com
Console.WriteLine(@"--- Day 3: Toboggan Trajectory ---");
// to solve this puzzle I had what i thought was a brilliant idea at the start.
// I'd represent each row of the terrain map as a circular array of char
// Since the terrain exends to the right indefinately it should work
// In the end I felt I'd written more code than really should have needed
// to come up with an answer. The use of Generics saves me having
// to care about actual number of rows in the puzzle input file,
// and while a screwdriver isn't always best tool for the job if that's
// what you have, use it.
//
// puzzle input is modelled as a circular array (endless grid) representing a patch of terrain
// the terrain repeats to the right
// I'll model the terrain map as a List of these one dimensional circular arrays
var rf = new ReadPuzzleInputFile();
var inputFile = rf.ReadFile();
List <CircularArrayOfChar> map = LoadMap(inputFile);
// use text compare tool to validate input file was correctly read in
// and matches puzzle terrain
// PrintMap(map);
// puzzle 1 slope is a given: right = 3, down = 1
TallyOfResults results = Puzzle1(map, 3, 1);
Console.WriteLine($"Puzzle 1 tree hits = {results.TreeHits}");
Console.WriteLine($"Puzzle 1 open space hits = {results.OpenSpaceHits}");
Console.WriteLine($"Puzzle 1 final value to the right = {results.ReachRight}");
// puzzle 2 test cases are
// Right 1, down 1.
// Right 3, down 1. (This is the slope you already checked.)
// Right 5, down 1.
// Right 7, down 1.
// Right 1, down 2.
// Puzzle1 will solve Puzzle2 just different input values for slope
int[,] testCases = new int[, ] {
{ 1, 1 }, { 3, 1 }, { 5, 1 }, { 7, 1 }, { 1, 2 }
};
List <TallyOfResults> resultsp2 = new List <TallyOfResults>();
for (int i = 0; i < 5; i++)
{
results = Puzzle1(map, testCases[i, 0], testCases[i, 1]);
Console.WriteLine($"Puzzle 2 test run {i} slope = ({testCases[i, 0]},{testCases[i, 1]}): tree hits = {results.TreeHits}");
Console.WriteLine($"Puzzle 2 test run {i}: open space hits = {results.OpenSpaceHits}");
Console.WriteLine($"Puzzle 2 test run {i}: final value to the right = {results.ReachRight}");
resultsp2.Add(results);
}
double totalTreeHits = 1; // i.e., init at 1: 1 multiplied by another number = other number
foreach (var item in resultsp2)
{
totalTreeHits *= item.TreeHits;
}
Console.WriteLine($"Puzzle 2 product of treeHits for each run = {totalTreeHits}");
}
