/* 

  Advent of Code 2023 Day 15 in Picat.

  https://adventofcode.com/2023/day/15

  This program was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import util.

main => go.

/*
  $ hyperfine 'picat 15.pi'
  Benchmark 1: picat 15.pi
    Time (mean ± σ):      40.8 ms ±   5.9 ms    [User: 25.3 ms, System: 15.4 ms]
    Range (min … max):    28.7 ms …  48.7 ms    52 runs

*/
go =>
  part1,
  part2,
  nl.


/*
  Part 1:
  $ hyperfine 'picat -g part1 15.pi'
  Benchmark 1: picat -g part1 15.pi
    Time (mean ± σ):      35.2 ms ±   7.1 ms    [User: 21.2 ms, System: 14.1 ms]
    Range (min … max):    17.6 ms …  53.2 ms    55 runs

*/
part1 =>
  File = "15.txt",
  println([hash(S) : S in read_file_lines(File).first.split(",\n")].sum).


table
hash(S) = Val =>
  Val = 0,
  foreach(C in S)
    Ord = ord(C),
    Val := ((Val + Ord) * 17) mod 256
  end.

/*
  Part 2:
  $ hyperfine 'picat -g part2 15.pi'
  Benchmark 1: picat -g part2 15.pi
    Time (mean ± σ):      40.3 ms ±   4.9 ms    [User: 24.7 ms, System: 15.5 ms]
    Range (min … max):    24.5 ms …  45.1 ms    60 runs

  See part2b/0 for another version.

*/
part2 =>
  File := "15.txt",  
  Ss = read_file_lines(File).first.split(",\n"),
  Map = new_map(),      % The slots
  LabelMap = new_map(), % Label -> Box
  foreach(S in Ss)
    if append(Label,"-",S) then
      if Box = LabelMap.get(Label,undef),Box != undef then
        % remove label
        Map.put(Box,[V : V in Map.get(Box), V != [Label,_]]),
        LabelMap.put(Label,undef)
      end
    elseif append(Label,"=",FocalLength,S) then
      Box = hash(Label),
      LF = [Label,FocalLength],
      if OldBox = LabelMap.get(Label,undef), OldBox != undef then
        % Replace in the same position
        Map.put(Box,[V : T in Map.get(Box), V = cond(T=[Label,_],LF,T)]),
        LabelMap.put(Label,Box)
      else
        % New 
        Map.put(Box,Map.get(Box,[]) ++ [LF]),
        LabelMap.put(Label,Box)        
      end
    end
  end,
  Sum = 0,
  foreach(I in 0..255)
    L = Map.get(I,undef), 
    if L != undef, L.len > 0 then
      foreach({[Label,FocalLength],J} in zip(L,1..L.len))
        Sum := Sum + (I+1) * J * FocalLength.to_int
      end
    end
  end,
  println(Sum).


/*
  Another take on part 2. 
  Same idea but with explicit calls to hashmap/[4-5] predicates.
  About the same time as part2/0.

  Benchmark 1: picat -g part2b 15.pi
    Time (mean ± σ):      38.5 ms ±   6.1 ms    [User: 24.6 ms, System: 13.9 ms]
    Range (min … max):    25.0 ms …  42.8 ms    61 runs
 
*/
part2b =>
  File := "15.txt",  
  Ss = read_file_lines(File).first.split(",\n"),
  Map = new_map(),      % The slots
  LabelMap = new_map(), % Label -> Box
  foreach(S in Ss)
    if append(Label,"-",S) then
      hashmap(Map,LabelMap,Label,delete)
    elseif append(Label,"=",FocalLength,S) then
      hashmap(Map,LabelMap,Label,FocalLength,append)
    end
  end,
  Sum = 0,
  foreach(I in 0..255)
    if L = Map.get(I,undef), L != undef then
      foreach({[Label,FocalLength],J} in zip(L,1..L.len))
        Sum := Sum + (I+1) * J * FocalLength.to_int
      end
    end
  end,
  println(Sum).

% delete
hashmap(Map,LabelMap,Label,delete) :-
  if Box = LabelMap.get(Label,undef), Box != undef then
    Map.put(Box,[V : V in Map.get(Box), V != [Label,_]]),
    LabelMap.put(Label,undef)
  end.

% append: new / replace
hashmap(Map,LabelMap,Label,FocalLength,append) :-
  Box = hash(Label),
  LF = [Label,FocalLength],
  if OldBox = LabelMap.get(Label,undef), OldBox != undef then
    % Replace in the same position
    Map.put(Box,[V : T in Map.get(Box), V = cond(T=[Label,_],LF,T)]),
    LabelMap.put(Label,Box)
  else
    % New 
    Map.put(Box,Map.get(Box,[]) ++ [LF]),
    LabelMap.put(Label,Box)        
  end.