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