module one

import Data.Maybe
import StdEnv
from Data.IntMap.Strict import :: IntMap
import qualified Data.IntMap.Strict as DM

input = [6,13,1,15,2,0]
input2 = [0,3,6]

Start = (one, two)

one = speak 2020 input
two = speak 30000000 input

//Old part I version
//speak :: Int [Int] -> Int
//speak num inp = speak` num (reverse inp)
//where
//	speak` 0 spoken = spoken!!length inp
//	speak` idx [ls:spoken] = case [i\\i<-[0..] & s<-spoken | s == ls] of
//		[] = speak` (idx-1) [0,ls:spoken]
//		[i:_] = speak` (idx-1) [i+1,ls:spoken]

speak :: Int [Int] -> Int
speak num inp = speak` (length inp) (last inp)
	('DM'.fromList [(num, idx)\\idx<-[0..] & num <-init inp])
where
	speak` :: !Int !Int !(IntMap Int) -> Int
	speak` idx last spoken
		| idx == num = last
		= speak` (idx+1) (maybe 0 (\i->idx-i-1) ('DM'.get last spoken)) ('DM'.put last (idx-1) spoken)