| 1 | 1 | def answer(question: str) -> int: |
| 2 | | pass |
| 2 | """ |
| 3 | Parse and evaluate a simple math word problem. |
| 4 | |
| 5 | Args: |
| 6 | question: A string representing a math word problem |
| 7 | |
| 8 | Returns: |
| 9 | int: The result of evaluating the math expression |
| 10 | |
| 11 | Raises: |
| 12 | ValueError: If the question is malformed, contains unknown operations, or is not a math question |
| 13 | """ |
| 14 | # Edge Case: Non-math questions |
| 15 | if not question.startswith("What is"): |
| 16 | raise ValueError("unknown operation") |
| 17 | |
| 18 | # Remove the "What is" prefix and the trailing question mark |
| 19 | expression = question[8:-1].strip() |
| 20 | |
| 21 | # Edge Case: Empty expression after "What is" |
| 22 | if not expression: |
| 23 | raise ValueError("syntax error") |
| 24 | |
| 25 | # Tokenize the expression |
| 26 | tokens = expression.split() |
| 27 | |
| 28 | # Edge Case: Expression with just a number |
| 29 | if len(tokens) == 1: |
| 30 | try: |
| 31 | return int(tokens[0]) |
| 32 | except ValueError: |
| 33 | # Edge Case: Single token that is not a valid integer |
| 34 | raise ValueError("syntax error") |
| 35 | |
| 36 | # Parse the first number |
| 37 | try: |
| 38 | result = int(tokens[0]) |
| 39 | except ValueError: |
| 40 | # Edge Case: First token is not a valid integer |
| 41 | raise ValueError("syntax error") |
| 42 | |
| 43 | i = 1 |
| 44 | |
| 45 | # Process operations from left to right |
| 46 | while i < len(tokens): |
| 47 | # Check if we have at least an operator |
| 48 | if i >= len(tokens): |
| 49 | raise ValueError("syntax error") |
| 50 | |
| 51 | operator = tokens[i] |
| 52 | |
| 53 | # Edge Case: Invalid operator |
| 54 | if operator not in ["plus", "minus", "multiplied", "divided"]: |
| 55 | # Check if it's a number (syntax error) or unknown operation |
| 56 | try: |
| 57 | int(operator) |
| 58 | # If we get here, it's a number, which means syntax error (two numbers in a row) |
| 59 | raise ValueError("syntax error") |
| 60 | except ValueError as e: |
| 61 | # Check if the error is from int() conversion or from our own raise |
| 62 | if str(e) == "syntax error": |
| 63 | # This is our own raise, re-raise it |
| 64 | raise |
| 65 | else: |
| 66 | # This means it's not a valid integer, so it's an unknown operation |
| 67 | raise ValueError("unknown operation") |
| 68 | |
| 69 | # Handle two-word operators |
| 70 | if operator in ["multiplied", "divided"]: |
| 71 | # Edge Case: Incomplete two-word operator |
| 72 | if i + 2 >= len(tokens): |
| 73 | raise ValueError("syntax error") |
| 74 | |
| 75 | # Edge Case: Invalid second word in two-word operator |
| 76 | if tokens[i+1] != "by": |
| 77 | raise ValueError("syntax error") |
| 78 | |
| 79 | i += 1 # Skip the "by" token |
| 80 | |
| 81 | # Check if we have an operand after the operator |
| 82 | if i + 1 >= len(tokens): |
| 83 | raise ValueError("syntax error") |
| 84 | |
| 85 | # Get the next number |
| 86 | try: |
| 87 | next_number = int(tokens[i+1]) |
| 88 | except ValueError: |
| 89 | # Edge Case: Operand is not a valid integer |
| 90 | raise ValueError("syntax error") |
| 91 | |
| 92 | # Perform the operation |
| 93 | if operator == "plus": |
| 94 | result += next_number |
| 95 | elif operator == "minus": |
| 96 | result -= next_number |
| 97 | elif operator == "multiplied": |
| 98 | result *= next_number |
| 99 | elif operator == "divided": |
| 100 | result //= next_number # Integer division as per examples |
| 101 | |
| 102 | i += 2 |
| 103 | |
| 104 | return result |