static int PartOne()
{
// #id @ x,y: wxh
var regex = new Regex(@"#(?<id>\d+) @ (?<x>\d+),(?<y>\d+): (?<w>\d+)x(?<h>\d+)");
string line;
var fabric = new int[1000, 1000];
// just fill the fabric matrix with the counts of claims and select anything greater than 1
using (var file = new StreamReader("input.txt"))
{
while ((line = file.ReadLine()) != null)
{
var parts = regex.Match(line);
var claim = new FabricClaim(
int.Parse(parts.Groups["id"].Value),
int.Parse(parts.Groups["x"].Value),
int.Parse(parts.Groups["y"].Value),
int.Parse(parts.Groups["w"].Value),
int.Parse(parts.Groups["h"].Value));
for (var i = claim.StartX; i < claim.EndX; i++)
{
for (var j = claim.StartY; j < claim.EndY; j++)
{
fabric[i, j]++;
}
}
}
}
// the cast here causes the array to get flattened and become enumerable
var query = from int item in fabric where item > 1 select item;
return(query.Count());
}
static int PartTwo()
{
var regex = new Regex(@"#(?<id>\d+) @ (?<x>\d+),(?<y>\d+): (?<w>\d+)x(?<h>\d+)");
string line;
var fabric = new int[1000, 1000];
var candidates = new HashSet <int>();
// just fill the fabric matrix with the counts of claims and select anything greater than 1
using (var file = new StreamReader("input.txt"))
{
while ((line = file.ReadLine()) != null)
{
var parts = regex.Match(line);
var claim = new FabricClaim(
int.Parse(parts.Groups["id"].Value),
int.Parse(parts.Groups["x"].Value),
int.Parse(parts.Groups["y"].Value),
int.Parse(parts.Groups["w"].Value),
int.Parse(parts.Groups["h"].Value));
var overlaps = false;
for (var i = claim.StartX; i < claim.EndX; i++)
{
for (var j = claim.StartY; j < claim.EndY; j++)
{
if (fabric[i, j] == 0)
{
// square is empty
fabric[i, j] = claim.ClaimId;
}
else
{
//not empty, remove the existing claim and set overlaps to true
candidates.Remove(fabric[i, j]);
overlaps = true;
}
}
}
// if not overlapping so far add to the list of candidates
if (!overlaps)
{
candidates.Add(claim.ClaimId);
}
}
}
//there should only be one left at this point
return(candidates.Single());
}