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# Day Twelve: Rain Risk
import os, strutils, sequtils, math, sugar
let input: string = paramStr(1)
let instructions: seq[tuple[action: char, value: int]] =
map(split(strip(readFile(input)), '\n'),
instruction => (instruction[0], parseInt(instruction[1..^1])))
var ferry, actual: tuple[latitude, longitude, bearing: int] = (0, 0, 0)
var waypoint: tuple[latitude, longitude: int] = (1, 10)
for instruction in instructions:
let value: int = instruction.value
let current: tuple[latitude, longitude: int] = waypoint
case instruction.action
of 'N':
inc(ferry.latitude, value)
inc(waypoint.latitude, value)
of 'S':
dec(ferry.latitude, value)
dec(waypoint.latitude, value)
of 'E':
inc(ferry.longitude, value)
inc(waypoint.longitude, value)
of 'W':
dec(ferry.longitude, value)
dec(waypoint.longitude, value)
of 'L':
inc(ferry.bearing, value)
let bearing: float = degToRad(toFloat(value))
case value
of 0, 180:
waypoint.latitude = sgn(cos(bearing)) * current.latitude
waypoint.longitude = sgn(cos(bearing)) * current.longitude
of 90, 270:
waypoint.latitude = sgn(sin(bearing)) * current.longitude
waypoint.longitude = -sgn(sin(bearing)) * current.latitude
else:
discard
of 'R':
dec(ferry.bearing, value)
let bearing: float = degToRad(toFloat(value))
case value
of 0, 180:
waypoint.latitude = sgn(cos(bearing)) * current.latitude
waypoint.longitude = sgn(cos(bearing)) * current.longitude
of 90, 270:
waypoint.latitude = -sgn(sin(bearing)) * current.longitude
waypoint.longitude = sgn(sin(bearing)) * current.latitude
else:
discard
of 'F':
let bearing: float = degToRad(toFloat(ferry.bearing))
if abs(cos(bearing)) == 1.0:
inc(ferry.longitude, sgn(cos(bearing)) * value)
elif abs(sin(bearing)) == 1.0:
inc(ferry.latitude, sgn(sin(bearing)) * value)
inc(actual.longitude, value * waypoint.longitude)
inc(actual.latitude, value * waypoint.latitude)
else:
discard
echo abs(ferry.longitude) + abs(ferry.latitude)
echo abs(actual.longitude) + abs(actual.latitude)
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