Day 14

1 files changed, 111 insertions, 0 deletions

diff --git a/day14/solution.nim b/day14/solution.nim
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+import strutils
+import sequtils
+import sets
+import strformat
+
+type Point = tuple[row: int, col: int]
+
+proc has(occupied: HashSet[Point], point: Point): bool =
+  point in occupied
+
+proc parsePoint(point: string): Point =
+  let tokens = point.split(",")
+  assert(tokens.len() == 2)
+  Point((tokens[1].parseInt(), tokens[0].parseInt()))
+
+proc parseLine(line: string): seq[Point] =
+  map(line.replace("-> ").split(" "), parsePoint)
+
+var maxRow = -1
+var maxCol = -1
+var minCol = 10000
+proc parseFile(content: string): HashSet[Point] =
+  let lines = content.strip.splitLines()
+  var rockLists = map(lines, parseLine)
+
+  for row in rockLists:
+    for point in row:
+      maxRow = max(maxRow, point.row)
+      maxCol = max(maxCol, point.col)
+      minCol = min(minCol, point.col)
+  
+  for rocks in rockLists:
+    # a = begin, b = end
+    for i, a in rocks[0..^2]:
+      let b = rocks[i+1]
+      echo fmt"a = {a}, b = {b}"
+      for col in min(a.col, b.col) .. max(a.col, b.col):
+        let toPush = Point((a.row, col))
+        result.incl(toPush)
+
+      for row in min(a.row, b.row) .. max(a.row, b.row):
+        let toPush = Point((row, a.col))
+        result.incl(toPush)
+
+proc draw(occupied: HashSet[Point]): void =
+  for row in 0 .. maxRow:
+    var line = ""
+    for col in minCol .. maxCol:
+      let current = Point((row, col))
+      line &= (if occupied.has(current): '#' else: '.')
+
+    echo line
+
+proc below(point: Point): Point =
+  Point((point.row+1, point.col))
+
+proc rbelow(point: Point): Point =
+  Point((point.row+1, point.col+1))
+
+proc lbelow(point: Point): Point =
+  Point((point.row+1, point.col-1))
+
+proc outOfBounds(point: Point): bool =
+  point.row > maxRow
+
+var part2 = false
+proc drop(occupied: var HashSet[Point], col: int): bool =
+  var point = Point((0, col))
+  
+  if part2 and occupied.has(point):
+    return false
+
+  while true:
+    let
+      below = point.below()
+      rbelow = point.rbelow()
+      lbelow = point.lbelow()
+
+    if point.outOfBounds():
+      if part2:
+        break
+      return false
+
+    if not occupied.has(below):
+      point = below
+      continue
+    if not occupied.has(lbelow):
+      point = lbelow
+      continue
+
+    if not occupied.has(rbelow):
+      point = rbelow
+      continue
+
+    break
+  occupied.incl(point)
+  return true
+
+proc solve(occupied: HashSet[Point]): int =
+  var occupied = occupied
+  while drop(occupied, 500):
+    result += 1
+
+let content = readFile("./input.txt")
+let occupied = parseFile(content)
+
+occupied.draw()
+echo fmt"{maxRow}, {minCol}-{maxCol}"
+echo solve(occupied)
+part2 = true
+echo solve(occupied)