day 4

Author: Gattaca1

day_4/day4.py

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+from typing import List
+
+def get_board() -> List[List[str]]:
+    board: List[List[str]] = []
+    with open('input', 'r') as file:
+        for line in file:
+            board.append(line.strip())
+
+    return board
+
+
+def find_words(board: List[List[str]]) -> int:
+    rows: int = len(board)
+    columns: int = len(board[0])
+
+    count: int = 0
+
+    for i in range(rows):
+        for j in range(columns):
+            # Initiate search only on X or S (looking for XMAS or SAMX)
+            if board[i][j] != 'X' and board[i][j] != 'S':
+                continue
+            
+            if j < columns - 3:
+                if look_right(board, i, j):
+                    count = count + 1
+            if i > 2:
+                if look_up(board, i, j):
+                    count = count + 1
+            if i > 2 and j < columns - 3:
+                if look_up_right(board, i, j):
+                    count = count + 1
+            if i > 2 and j > 2:
+                if look_up_left(board, i, j):
+                    count = count + 1
+    return count
+
+
+def look_up(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i][j] == 'X' and board[i-1][j] == 'M' and board[i-2][j] == 'A' and board[i-3][j] == 'S':
+        return True
+    if board[i][j] == 'S' and board[i-1][j] == 'A' and board[i-2][j] == 'M' and board[i-3][j] == 'X':
+        return True
+    return False
+
+
+def look_up_right(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i][j] == 'X' and board[i-1][j+1] == 'M' and board[i-2][j+2] == 'A' and board[i-3][j+3] == 'S':
+        return True
+    if board[i][j] == 'S' and board[i-1][j+1] == 'A' and board[i-2][j+2] == 'M' and board[i-3][j+3] == 'X':
+        return True
+    return False
+
+
+def look_up_left(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i][j] == 'X' and board[i-1][j-1] == 'M' and board[i-2][j-2] == 'A' and board[i-3][j-3] == 'S':
+        return True
+    if board[i][j] == 'S' and board[i-1][j-1] == 'A' and board[i-2][j-2] == 'M' and board[i-3][j-3] == 'X':
+        return True
+    return False
+
+
+def look_right(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i][j] == 'X' and board[i][j+1] == 'M' and board[i][j+2] == 'A' and board[i][j+3] == 'S':
+        return True
+    if board[i][j] == 'S' and board[i][j+1] == 'A' and board[i][j+2] == 'M' and board[i][j+3] == 'X':
+        return True
+    return False
+
+
+def find_mas_cross(board: List[List[str]]) -> int:
+    rows: int = len(board)
+    columns: int = len(board[0])
+
+    count: int = 0
+
+    for i in range(rows):
+        for j in range(columns):
+            # Initiate search only on A
+            if board[i][j] != 'A':
+                continue
+            
+            # Don't look for an 'A' on the outer borders since the cross can't appear there
+            if i > 0 and i < rows - 1 and j > 0 and j < columns - 1:
+                if positive_slope_mas(board, i, j) and negative_slope_mas(board, i, j):
+                    count = count + 1
+    return count
+
+
+def positive_slope_mas(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i-1][j+1] == 'M' and board[i+1][j-1] == 'S':
+        return True
+    if board[i-1][j+1] == 'S' and board[i+1][j-1] == 'M':
+        return True
+    return False
+
+
+def negative_slope_mas(board: List[List[str]], i: int, j: int) -> bool:
+    if board[i-1][j-1] == 'M' and board[i+1][j+1] == 'S':
+        return True
+    if board[i-1][j-1] == 'S' and board[i+1][j+1] == 'M':
+        return True
+    return False
+
+
+def main():
+    board = get_board()
+    #num_words = find_words(board) # Part 1
+    num_words = find_mas_cross(board) # Part 2
+    print(num_words)
+
+
+if __name__ == "__main__":
+    main()