Day 23 part 1 done

2021/nim/common.nim

@@ -47,14 +47,14 @@ proc doDay*[T, X](
   expectedPart1: X,
   expectedPart2: X): void =
 
-  when not defined(release):
+  # when not defined(release):
   var p1 = testInput.part1()
   echo "Day ", day, " Part 1: ", p1, " (Expected: ", expectedPart1, ")"
   doAssert p1 == expectedPart1
 
   time(&"Day {day} Part 1"): echo day.inputLoader().part1()
 
-  when not defined(release):
+  # when not defined(release):
   var p2 = testInput.part2()
   echo "Day ", day, " Part 2: ", p2, " (Expected: ", expectedPart2, ")"
   doAssert p2 == expectedPart2

2021/nim/day23.nim

@@ -53,7 +53,6 @@ proc path(s: AmphipodCaveState, ai: int, goal: Vec2): seq[Vec2] =
 proc move(s: AmphipodCaveState, ai: int, p: Vec2): (AmphipodCaveState, uint64) =
   var newState = s
   newState[ai].pos = p
-  echo &"Moving {ai} from {s[ai].pos} to {p}"
   (newState, s.path(ai, p).len.uint64 * s[ai].breed.weight.uint64)
 
 proc spaceOccupied(s: AmphipodCaveState, p: Vec2): bool =
@@ -62,30 +61,32 @@ proc spaceOccupied(s: AmphipodCaveState, p: Vec2): bool =
 proc canMoveTo(s: AmphipodCaveState, ai: int, goal: Vec2): bool =
   let a = s[ai]
   let pos = s[ai].pos
-  # can't move anywhere but home once we've left
+  # echo " -> once in the hallway, we can't move somewhere else in the hallway"
   if pos.y == 0 and goal.y == 0: return false
-  # no blocking
+  # echo " -> no blocking"
   if goal.y == 0 and homeSet.contains(goal.x): return false
-  # non-positions
+  # echo " -> non-positions"
   if goal.y > 0 and not homeSet.contains(goal.x): return false
-  # can't leave empty spots below when going home
+  # echo " -> can't leave empty spots below when going home"
   if goal.y == 1 and not s.spaceOccupied(v2(goal.x, 2)): return false
-  # can't enter home if occupied by another breed
-  if goal.y == 1:
+  # echo " -> can't enter home if occupied by another breed"
+  if goal.y > 0:
     for sib in s:
+      if sib.breed == a.breed: continue
       if sib.pos.x == goal.x and sib.pos.y > goal.y: return false
-  # can't enter somebody else's home
+  # echo " -> can't enter somebody else's home"
   if goal.y > 0 and goal.x != a.breed.home: return false
-  # can't move through any occupied positions
+  # echo " -> can't move through any occupied positions"
   let path = s.path(ai, goal)
   if path.anyIt(s.spaceOccupied(it)): return false
+  # echo " -> Allowed!"
   true
 
 proc isWin(s: AmphipodCaveState): bool =
   result = s.allIt(it.pos.x == it.breed.home and it.pos.y > 0)
-  if result:
-    echo s
-    echo "I WON"
+  # if result:
+    # echo s
+    # echo "I WON"
 
 proc possibleMoves(s: AmphipodCaveState, ai: int): HashSet[Vec2] =
   let a = s[ai]
@@ -98,27 +99,32 @@ proc possibleMoves(s: AmphipodCaveState, ai: int): HashSet[Vec2] =
 
 proc getByPos(s: AmphipodCaveState, pos: Vec2): Option[Amphipod] = s.findFirstO(a => a.pos == pos)
 proc isHome(a: Amphipod): bool = a.pos.x == a.breed.home and a.pos.y > 0
+
 proc doneMoving(s: AmphipodCaveState, ai: int): bool =
   let a = s[ai]
   if a.isHome and a.pos.y >= 2: return true
-  let below = s.getByPos((x: a.pos.x, y: 1))
+  let below = s.getByPos((x: a.pos.x, y: 2))
   if below.isSome: return a.isHome and below.get.isHome
 
-var cheapestWins = newTable[AmphipodCaveState, uint64]()
+var cheapestWins = newTable[AmphipodCaveState, (uint64, uint64)]()
 proc cheapestWin(s: AmphipodCaveState, cost: uint64, depth = 0): uint64 =
   result = uint64.high
-  echo &"cheapestWin: {cost} {depth}\n{s}"
-  if cheapestWins.hasKey s: return cheapestWins[s]
-  if s.isWin or cost > 50000: return cost
+  # echo &"cheapestWin: {cost} {depth}\n{s}"
+  if cheapestWins.hasKey s:
+    # echo &"cache hit for {s}: {cheapestWins[s]}"
+    if cheapestWins[s][0] <= cost:
+      return cheapestWins[s][1]
+  if s.isWin or cost > 400000: return cost
   var costs = initHashSet[uint64]()
   for ai,a in s:
     if s.doneMoving(ai): continue
     for p in s.possibleMoves ai:
       if not s.canMoveTo(ai, p): continue
+      # echo &"Moving {ai} from {a.pos} to {p} at turn {depth}"
       let (newState, moveCost) = s.move(ai, p)
       costs.incl newState.cheapestWin(cost + moveCost, depth + 1)
   for c in costs: result = min(result, c)
-  cheapestWins[s] = result
+  cheapestWins[s] = (cost, result)
 
 proc testMoves(state: AmphipodCaveState, moves: seq[(int, Vec2)]) =
   var s = state
@@ -126,6 +132,7 @@ proc testMoves(state: AmphipodCaveState, moves: seq[(int, Vec2)]) =
   for m in moves:
     echo s
     let (ai, goal) = m
+    let doneMoving = s.doneMoving(ai)
     let suggestions = s.possibleMoves(ai)
     echo suggestions
     var sugs = @["...........", "  . . . .", "  . . . .", ""]
@@ -136,35 +143,26 @@ proc testMoves(state: AmphipodCaveState, moves: seq[(int, Vec2)]) =
     echo sugs.join("\n")
     let allowed = s.canMoveTo(ai, goal)
     let suggested = suggestions.contains goal
-    echo &"Can move {ai} from {s[ai].pos} to {goal}: allowed: {allowed}, suggested: {suggested}"
+    echo &"Can move {ai} from {s[ai].pos} to {goal}: allowed: {allowed}, suggested: {suggested}, doneMoving: {doneMoving}"
     var (newState, moveCost) = s.move(ai, goal)
     cost += moveCost
     s = newState
     echo &"Did we win? {s.isWin} -- Cost so far: {cost}"
 
 proc p1(input: Lines): uint64 =
-  echo input.parseCaveState
-  var s = input.parseCaveState
-  s.testMoves(@[
-    (2, (x: 3, y: 0)),
-    (1, (x: 6, y: 1)),
-    (5, (x: 5, y: 0)),
-    (2, v2(4, 2)),
-    (0, v2(4, 1)),
-    (3, v2(7, 0)),
-    (7, v2(9, 0)),
-    (3, v2(8, 2)),
-    (5, v2(8, 1)),
-    (7, v2(2, 1)),
-  ])
-  echo "Crunching..."
   input.parseCaveState.cheapestWin(0)
 
+proc p2(input: Lines): uint64 =
+  var unfoldedInput = input
+  unfoldedInput.insert("  #D#C#B#A#", 1)
+  unfoldedInput.insert("  #D#C#B#A#", 2)
+  unfoldedInput.parseCaveState.cheapestWin(0)
+
 const rt = ("""
 #############
 #...........#
 ###B#C#B#D###
   #A#D#C#A#
   #########
-""".strip().split('\n'), 12521'u64, 0'u64)
-doDayX 23, (n: int) => n.loadInput, p1, p1, rt
+""".strip().split('\n'), 12521'u64, 44169'u64)
+doDayX 23, (n: int) => n.loadInput, p1, p2, rt