| 1 | 1 | def answer(question: str) -> int: |
| 2 | | pass |
| 2 | # Edge Case: Empty question |
| 3 | if not question: |
| 4 | raise ValueError("syntax error") |
| 5 | |
| 6 | # Edge Case: Non-math questions |
| 7 | if not question.startswith("What is"): |
| 8 | raise ValueError("unknown operation") |
| 9 | |
| 10 | # Remove the "What is " prefix and the trailing "?" |
| 11 | if not question.endswith('?'): |
| 12 | raise ValueError("syntax error") |
| 13 | expression = question[8:-1].strip() |
| 14 | |
| 15 | # Edge Case: Empty expression after "What is" |
| 16 | if not expression: |
| 17 | raise ValueError("syntax error") |
| 18 | |
| 19 | # Split the expression into tokens |
| 20 | tokens = expression.split() |
| 21 | |
| 22 | # Edge Case: Invalid syntax - operation at the beginning |
| 23 | if tokens[0] in ["plus", "minus", "multiplied", "divided"]: |
| 24 | raise ValueError("syntax error") |
| 25 | |
| 26 | # Try to parse the first number |
| 27 | try: |
| 28 | result = int(tokens[0]) |
| 29 | except ValueError: |
| 30 | # Edge Case: First token is not a number |
| 31 | raise ValueError("syntax error") |
| 32 | |
| 33 | i = 1 |
| 34 | while i < len(tokens): |
| 35 | operation = tokens[i] |
| 36 | |
| 37 | # Edge Case: Invalid syntax - unexpected token |
| 38 | # First check if it's a valid operation |
| 39 | if operation not in ["plus", "minus", "multiplied", "divided"]: |
| 40 | # If it's not a valid operation, check if it's a number |
| 41 | try: |
| 42 | int(operation) |
| 43 | # If it's a number, this is invalid syntax (number in operation position) |
| 44 | raise ValueError("syntax error") |
| 45 | except ValueError as e: |
| 46 | # If conversion to int fails, it's not a number, so it's an unknown operation |
| 47 | # But we need to be careful not to catch our own "syntax error" exception |
| 48 | if str(e) == "syntax error": |
| 49 | raise |
| 50 | # If it's not a number, it's an unknown operation |
| 51 | raise ValueError("unknown operation") |
| 52 | |
| 53 | # Edge Case: Incomplete expression - operation without operand |
| 54 | if i + 1 >= len(tokens): |
| 55 | raise ValueError("syntax error") |
| 56 | |
| 57 | # Edge Case: Invalid syntax - consecutive operations |
| 58 | if operation in ["plus", "minus", "multiplied", "divided"] and i > 0 and tokens[i-1] in ["plus", "minus", "multiplied", "divided"]: |
| 59 | raise ValueError("syntax error") |
| 60 | |
| 61 | # Perform the operation |
| 62 | if operation == "plus": |
| 63 | # Get the operand |
| 64 | try: |
| 65 | operand = int(tokens[i + 1]) |
| 66 | except ValueError: |
| 67 | # Edge Case: Operand is not a number |
| 68 | raise ValueError("syntax error") |
| 69 | result += operand |
| 70 | elif operation == "minus": |
| 71 | # Get the operand |
| 72 | try: |
| 73 | operand = int(tokens[i + 1]) |
| 74 | except ValueError: |
| 75 | # Edge Case: Operand is not a number |
| 76 | raise ValueError("syntax error") |
| 77 | result -= operand |
| 78 | elif operation == "multiplied": |
| 79 | # Edge Case: Check for correct "multiplied by" syntax |
| 80 | if i + 1 >= len(tokens) or tokens[i + 1] != "by": |
| 81 | raise ValueError("syntax error") |
| 82 | # Check if there's an operand after "by" |
| 83 | if i + 2 >= len(tokens): |
| 84 | raise ValueError("syntax error") |
| 85 | # Get the operand |
| 86 | try: |
| 87 | operand = int(tokens[i + 2]) |
| 88 | except ValueError: |
| 89 | # Edge Case: Operand is not a number |
| 90 | raise ValueError("syntax error") |
| 91 | result *= operand |
| 92 | i += 1 # Skip the "by" token |
| 93 | elif operation == "divided": |
| 94 | # Edge Case: Check for correct "divided by" syntax |
| 95 | if i + 1 >= len(tokens) or tokens[i + 1] != "by": |
| 96 | raise ValueError("syntax error") |
| 97 | # Check if there's an operand after "by" |
| 98 | if i + 2 >= len(tokens): |
| 99 | raise ValueError("syntax error") |
| 100 | # Get the operand |
| 101 | try: |
| 102 | operand = int(tokens[i + 2]) |
| 103 | except ValueError: |
| 104 | # Edge Case: Operand is not a number |
| 105 | raise ValueError("syntax error") |
| 106 | result //= operand |
| 107 | i += 2 # Skip the "by" token and operand |
| 108 | else: |
| 109 | # This should never happen due to earlier validation, but just in case |
| 110 | raise ValueError("unknown operation") |
| 111 | |
| 112 | i += 2 |
| 113 | |
| 114 | return result |
| 115 | # Handled Edge Cases: Non-math questions, Empty expression, Invalid syntax (operation at beginning, consecutive operations, unexpected tokens), Unknown operations, Incomplete expressions, Invalid operands, Incorrect "multiplied by"/"divided by" syntax |