2021/4/second.nim

@@ -0,0 +1,43 @@
+import
+  ../../adventofcode,
+  math,
+  sequtils,
+  strutils,
+  strformat
+  
+import
+  x/board
+  
+let input = adventofcode.getInput(2021, 4)
+let lines = input.splitLines()[0 .. ^2]
+
+let drawn = lines[0].split(",").mapIt(it.parseInt())
+var currentlyDrawn: seq[int] = @[]
+var boards: seq[Board] = @[]
+
+# Determinate boards from our input
+var currBoard = newBoard()
+for line in lines[2 .. ^1]:
+  if line.len() != 0:
+    currBoard.grid.add line.split(" ").filterIt(it.len() > 0).mapIt(it.parseInt())
+    
+  else:
+    boards.add currBoard
+    currBoard = newBoard()
+    
+var winningBoards: seq[Board]
+while currentlyDrawn.len() != drawn.len() and winningBoards.len() < boards.len():
+  let next = drawn[currentlyDrawn.len()]
+  currentlyDrawn.add next
+  
+  for board in boards:
+    board.markNumber next
+    
+    if board.winning and not winningBoards.contains board:
+      winningBoards.add board
+
+let lastWinningBoard = winningBoards[^1]
+let lastWinningBoardScore = currentlyDrawn[^1] * math.sum lastWinningBoard.getUnmarkedNumbers()
+
+echo fmt"Boards: {boards.len()}"
+echo fmt"Answer: {lastWinningBoardScore}"

2021/5/both.nim

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+import
+  ../../adventofcode,
+  hashes,
+  sequtils,
+  strutils,
+  strformat,
+  tables
+
+type
+  Grid = TableRef[Point, int]
+
+  HydrothermalVent = object
+    x1, x2, y1, y2: int
+
+  Point = object
+    x, y: int
+    
+## https://stackoverflow.com/questions/919612/mapping-two-integers-to-one-in-a-unique-and-deterministic-way
+#[
+A = a >= 0 ? 2 * a : -2 * a - 1;
+B = b >= 0 ? 2 * b : -2 * b - 1;
+A >= B ? A * A + A + B : A + B * B;
+]#
+proc hash(p: Point): Hash =
+  let A =
+    if p.x >= 0: 2 * p.x
+    else: -2 * p.x - 1
+  let B =
+    if p.y >= 0: 2 * p.y
+    else: -2 * p.y - 1
+  return
+    if A >= B: A * A + A + B
+    else: A + B * B
+
+proc getPoints(v: HydrothermalVent): seq[Point] =
+  let xd = max(v.x1, v.x2) - min(v.x1, v.x2)
+  let yd = max(v.y1, v.y2) - min(v.y1, v.y2)
+  when defined(second):
+    let xoffset = v.x2 - v.x1
+    let yoffset = v.y2 - v.y1
+
+  if xd != 0 and v.y1 == v.y2:
+    for i in 0 .. xd:
+      result.add Point(x: min(v.x1, v.x2) + i, y: v.y1)
+
+  elif yd != 0 and v.x1 == v.x2:
+    for i in 0 .. yd:
+      result.add Point(x: v.x1, y: min(v.y1, v.y2) + i)
+
+  else:
+    when defined(second):
+      # TODO:
+      if xoffset < 0:
+        for i in 0 .. xd:
+          result.add Point(
+            x: min(v.x1, v.x2) + i,
+            y: max(v.y1, v.y2) - i
+          )
+      
+      else:
+        for i in 0 .. yd:
+          result.add Point(
+            x: max(v.x1, v.x2) + i,
+            y: min(v.y1, v.y2) + i
+          )
+  
+proc parseInput(input: string): seq[HydrothermalVent] = 
+  for line in input.splitLines()[0 .. ^2]:
+    let coords = line.split(" -> ").mapIt(it.split(",").mapIt(it.parseInt()))
+    result.add HydrothermalVent(
+      x1: coords[0][0], y1: coords[0][1], x2: coords[1][0], y2: coords[1][1] 
+    )
+    
+static:
+  let dummyVent = HydrothermalVent(x1: 9, y1: 7, x2: 7, y2: 9)
+  for point in dummyVent.getPoints():
+    echo $point
+  
+let input = adventofcode.getInput(2021, 5)
+let vents = input.parseInput()
+let grid = Grid()
+
+for vent in vents:
+  let points = vent.getPoints()
+  for point in points:
+    if not grid.hasKey point:
+      grid[point] = 1
+    else:
+      grid[point] += 1
+      
+let overlappingPoints = toSeq(grid.values).countIt(it > 1)
+echo fmt"Answer: {overlappingPoints}"