advent-of-code/2021/nim/day2.nim

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Nim
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import std/[strutils, sequtils]
import ./common
type SubmarineCommand = enum
Forward, Up, Down
2021-12-02 11:16:53 -06:00
proc parseArg(c: char): int = c.int() - int('0')
proc parseSubmarineCommand(l: string): (SubmarineCommand, int) =
case l[0]:
# since each arg is only one char, we can use this much faster method to
# convert to an integer
of 'd': return (Down, l[5].parseArg())
of 'u': return (Up, l[3].parseArg())
else: return (Forward, l[8].parseArg())
proc submarineCommands(inputs: seq[string]): int =
var x, y = 0
for (cmd, arg) in inputs.map(parseSubmarineCommand):
case cmd:
of Up: y -= arg
of Down: y += arg
of Forward: x += arg
x * y
proc submarineCommandsWithAim(inputs: seq[string]): int =
var x, y, aim = 0
for (cmd, arg) in inputs.map(parseSubmarineCommand):
case cmd:
of Up: aim -= arg
of Down: aim += arg
of Forward:
x += arg
y += aim * arg
x * y
let input = 2.loadInput()
time("submarineCommands part 1"): echo input.submarineCommands()
time("submarineCommandsWithAim part 2"): echo input.submarineCommandsWithAim()
when not defined(release):
static:
let testInput = @[
"forward 5",
"down 5",
"forward 8",
"up 3",
"down 8",
"forward 2",
]
doAssert testInput.submarineCommands() == 150
doAssert testInput.submarineCommandsWithAim() == 900