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import strutils
import sequtils
import sets
type Move = tuple[Direction: char, Distance: int]
type Position = tuple[r: int, c: int]
proc parse(content: seq[string]): seq[Move] =
let moves = map(content,
proc (line: string): Move =
let temp = line.split(" ")
(temp[0][0], temp[1].parseInt())
)
return moves
proc move(rope: var seq[Position], uniqPositions: var HashSet[Position]): void =
for i in 1 ..< rope.len():
# rope[i-1] = leader
# rope[i] = follower
let roffset = rope[i-1].r - rope[i].r
let coffset = rope[i-1].c - rope[i].c
if roffset in [2, -2]:
rope[i].r += int(roffset/2)
if coffset in [-1, 1]:
rope[i].c = rope[i-1].c
if coffset in [2, -2]:
rope[i].c += int(coffset/2)
if roffset in [-1, 1]:
rope[i].r = rope[i-1].r
uniqPositions.incl(rope[rope.len()-1])
proc emulate(moves: seq[Move], len = 2): int =
var rope = newSeq[Position](len)
var uniqPositions: HashSet[Position]
init(uniqPositions)
echo rope
for move in moves:
for i in 1 .. move.Distance:
case move.Direction:
of 'U':
rope[0].r -= 1
of 'R':
rope[0].c += 1
of 'D':
rope[0].r += 1
of 'L':
rope[0].c -= 1
else:
assert(false)
move(rope, uniqPositions)
return len(uniqPositions)
let content = readFile("./input.txt").strip().splitLines()
let moves = parse(content)
echo emulate(moves)
echo emulate(moves, 10)
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