2021/11/both.nim

@@ -0,0 +1,67 @@
+import
+  std/sequtils,
+  std/strformat,
+  std/strutils
+
+import
+  ../../adventofcode
+  
+let input = adventofcode.getInput(2021, 11)
+var grid: seq[seq[int]] = block:
+  input.splitLines().mapIt(it.mapIt(parseInt $it))
+  
+var steps = 0
+var flashes = 0
+  
+proc inc(row, col: int)
+proc flash(row, col: int)
+  
+proc inc(row, col: int) =
+  try:
+    grid[row][col] += 1
+    if grid[row][col] == 10:
+      flash(row, col)
+  except IndexDefect: return
+  
+proc flash(row, col: int) =
+  flashes += 1
+  inc(row, col - 1)
+  inc(row, col + 1)
+  inc(row - 1, col)
+  inc(row + 1, col)
+  inc(row - 1, col - 1)
+  inc(row + 1, col + 1)
+  inc(row - 1, col + 1)
+  inc(row + 1, col - 1)
+
+proc resetFlashes() =
+  for row in 0 .. grid.high():
+    for col in 0 .. grid[row].high():
+      if grid[row][col] > 9:
+        grid[row][col] = 0
+        
+when defined(second):
+  proc areTheyAllFlashing(): bool =
+    result = true
+    for row in 0 .. grid.high():
+      for col in 0 .. grid[row].high():
+        if grid[row][col] != 0:
+          return false
+  
+proc forwardStep() =
+  steps += 1
+  for row in 0 .. grid.high():
+    for col in 0 .. grid[row].high():
+      inc(row, col)
+  resetFlashes()
+      
+when not defined(second):
+  while steps < 100:
+    forwardStep()
+
+  echo fmt"Answer: {flashes}"
+else:
+  while not areTheyAllFlashing():
+    forwardStep()
+
+  echo fmt"Answer: {steps}"