adventofcode2021/day06/part1.nim

47 lines
1.3 KiB
Nim

# Copyright 2021 Christian Ulrich
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# usage: ./part1 < input
import sequtils
import strutils
const Days = 80
proc predictLanternfishCount(): int =
var
timers = readLine(stdin).split(',').mapIt(uint8(parseUint(it)))
newTimers: seq[uint8]
for day in 0 ..< Days:
newTimers.setLen(0)
for timer in timers.mitems():
if timer == 0'u8:
newTimers.add(8'u8)
timer = 6'u8
else:
timer.dec()
timers.add(newTimers)
result = timers.len()
proc main(): int =
try:
echo predictLanternfishCount()
except Exception as error:
echo error.msg
result = -1
when isMainModule:
quit(main())