December 4th (#3)

Author: plbrault

04.py

@@ -0,0 +1,108 @@
+def check_for_xmas(puzzle, row, col):
+  if puzzle[row][col] != 'X':
+    return False
+  num_occurrences = 0
+  # Horizontal backwards
+  if col > 2:
+    if (
+      puzzle[row][col-1] == 'M'
+      and puzzle[row][col-2] == 'A'
+      and puzzle[row][col-3] == 'S'
+    ):
+      num_occurrences += 1
+  # Vertical upwards
+  if row > 2:
+    if (
+      puzzle[row-1][col] == 'M'
+      and puzzle[row-2][col] == 'A'
+      and puzzle[row-3][col] == 'S'
+    ):
+      num_occurrences += 1
+  # Horizontal forwards
+  if len(puzzle[row]) - col > 3:
+    if (
+      puzzle[row][col+1] == 'M'
+      and puzzle[row][col+2] == 'A'
+      and puzzle[row][col+3] == 'S'
+    ):
+      num_occurrences += 1
+  # Vertical downwards
+  if len(puzzle) - row > 3:
+    if (
+      puzzle[row+1][col] == 'M'
+      and puzzle[row+2][col] == 'A'
+      and puzzle[row+3][col] == 'S'
+    ):
+      num_occurrences += 1
+  # Diagonal upwards left
+  if row > 2 and col > 2:
+    if (
+      puzzle[row-1][col-1] == 'M'
+      and puzzle[row-2][col-2] == 'A'
+      and puzzle[row-3][col-3] == 'S'
+    ):
+      num_occurrences += 1
+  # Diagonal upwards right
+  if row > 2 and len(puzzle[row]) - col > 3:
+    if (
+      puzzle[row-1][col+1] == 'M'
+      and puzzle[row-2][col+2] == 'A'
+      and puzzle[row-3][col+3] == 'S'
+    ):
+      num_occurrences += 1
+  # Diagonal downwards left
+  if len(puzzle) - row > 3 and col > 2:
+    if (
+      puzzle[row+1][col-1] == 'M'
+      and puzzle[row+2][col-2] == 'A'
+      and puzzle[row+3][col-3] == 'S'
+    ):
+      num_occurrences += 1
+  # Diagonal downwards right
+  if len(puzzle) - row > 3 and len(puzzle[row]) - col > 3:
+    if (
+      puzzle[row+1][col+1] == 'M'
+      and puzzle[row+2][col+2] == 'A'
+      and puzzle[row+3][col+3] == 'S'
+    ):
+      num_occurrences += 1
+  return num_occurrences
+
+def check_for_x_mas(puzzle, row, col):
+  if puzzle[row][col] != 'A':
+    return False
+  if row < 1 or col < 1 or row > len(puzzle) - 2 or col > len(puzzle[row]) - 2:
+    return False
+  if (
+    (
+      (puzzle[row-1][col-1] == 'M' and puzzle[row+1][col+1] == 'S')
+      or (puzzle[row-1][col-1] == 'S' and puzzle[row+1][col+1] == 'M')
+    )
+    and
+    (
+      (puzzle[row-1][col+1] == 'M' and puzzle[row+1][col-1] == 'S')
+      or (puzzle[row-1][col+1] == 'S' and puzzle[row+1][col-1] == 'M')
+    )
+  ):
+    return True
+  return False
+
+puzzle = []
+
+with open('input.txt', 'r') as file:
+  for line in file:
+    puzzle.append(list(line.strip()))
+
+# Part 1
+xmas_count = 0
+for row in range(len(puzzle)):
+  for col in range(len(puzzle[row])):
+    xmas_count += check_for_xmas(puzzle, row, col)
+print('Number of XMAS occurrences:', xmas_count)
+
+# Part 2
+x_mas_count = 0
+for row in range(len(puzzle)):
+  for col in range(len(puzzle[row])):
+    x_mas_count += int(check_for_x_mas(puzzle, row, col))
+print ('Number of X-MAS occurrences:', x_mas_count)