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www.mikescher.com/www/statics/aoc/2022/09_solution-2.nim

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2022-12-09 11:54:36 +01:00
import std/strutils
import std/sequtils
import system
type Pos = object
X: int
Y: int
type Rope = object
Knots: array[10, Pos]
proc move_rope(input: Rope, vec: Pos): Rope =
var rope = input
rope.Knots[0].X += vec.X
rope.Knots[0].Y += vec.Y
for i in 0 ..< 9:
let deltaX = rope.Knots[i].X - rope.Knots[i+1].X
let deltaY = rope.Knots[i].Y - rope.Knots[i+1].Y
if not (abs(deltaX) >= 2 or abs(deltaY) >= 2): return rope
if deltaX > 0:
rope.Knots[i+1].X += 1
elif deltaX < 0:
rope.Knots[i+1].X -= 1
if deltaY > 0:
rope.Knots[i+1].Y += 1
elif deltaY < 0:
rope.Knots[i+1].Y -= 1
return rope
proc run09_2(): string =
const input = staticRead"../input/day09.txt"
let lines = splitLines(input).filter(proc(p: string): bool = p != "")
let Z = Pos(X: 0, Y: 0)
var rope = Rope(Knots: [Z, Z, Z, Z, Z, Z, Z, Z, Z, Z])
var tailposmap = @[rope.Knots[9]]
for line in lines:
let dir = case line.split(" ")[0][0]:
of 'U': Pos(X: 00, Y: -1)
of 'D': Pos(X: 00, Y: +1)
of 'L': Pos(X: -1, Y: 00)
of 'R': Pos(X: +1, Y: 00)
else: Pos(X: 00, Y: 00)
let cnt = parseInt(line.split(" ")[1])
for _ in 0 ..< cnt:
rope = move_rope(rope, dir)
tailposmap.add(rope.Knots[9])
return tailposmap.deduplicate().len().intToStr()
when not defined(js):
echo run09_2()
else:
proc js_run09_2(): cstring {.exportc.} =
return cstring(run09_2())