private IEnumerable <Intersection> ParseWire(int id, string[] wireSegments)
{
List <Intersection> intersections = new List <Intersection>();
Point from = Point.Origin; // Start @(0,0)
var wireDistance = 0;
foreach (var segment in wireSegments)
{
var length = int.Parse(segment.Substring(1));
var to = (segment[0]) switch
{
'U' => new Point(from.x, from.y + length),
'D' => new Point(from.x, from.y - length),
'L' => new Point(from.x - length, from.y),
'R' => new Point(from.x + length, from.y),
_ => throw new ArgumentOutOfRangeException(nameof(segment)),
};
var seg = new WireSegment(id, from, to, wireDistance);
wireDistance += length; // Add segment length to wire distance
intersections.AddRange(segments
.Where(s => s.wire != seg.wire && s.Intersects(seg)) // The same wire cannot intersect itself
.Select(s => new Intersection(s, seg, s.IntersectsAt(seg))));
segments.Add(seg);
from = to;
}
return(intersections);
}
public Point IntersectsAt(WireSegment other)
{
var y = from.y == to.y ? from.y : other.from.y; // use y from horizontal segment
var x = from.x == to.x ? from.x : other.from.x; // use x from vertical segment
return(new Point(x, y));
}
public bool Intersects(WireSegment other)
{
if (from.Equals(Point.Origin) && other.from.Equals(Point.Origin))
{
return(false); // Do not count origin
}
return(!(Right < other.Left || Left > other.Right || Bottom > other.Top || Top < other.Bottom));
}
public Intersection(WireSegment seg1, WireSegment seg2, Point intersection)
{
this.seg1 = seg1;
this.seg2 = seg2;
this.intersection = intersection;
}