| 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: Empty or None input |
| 15 | if not question: |
| 16 | raise ValueError("syntax error") |
| 17 | |
| 18 | # Edge Case: Question doesn't end with a question mark |
| 19 | if not question.endswith("?"): |
| 20 | raise ValueError("syntax error") |
| 21 | |
| 22 | # Edge Case: Question doesn't start with "What is" |
| 23 | if not question.startswith("What is"): |
| 24 | raise ValueError("syntax error") |
| 25 | |
| 26 | # Remove "What is" prefix and question mark |
| 27 | expression = question[8:].rstrip('?').strip() |
| 28 | |
| 29 | # Edge Case: Empty expression after removing prefix |
| 30 | if not expression: |
| 31 | raise ValueError("syntax error") |
| 32 | |
| 33 | # Split the expression into tokens |
| 34 | tokens = expression.split() |
| 35 | |
| 36 | # Edge Case: No tokens |
| 37 | if not tokens: |
| 38 | raise ValueError("syntax error") |
| 39 | |
| 40 | # Parse the first number |
| 41 | try: |
| 42 | result = int(tokens[0]) |
| 43 | position = 1 |
| 44 | except ValueError: |
| 45 | # Edge Case: First token is not a number |
| 46 | raise ValueError("syntax error") |
| 47 | |
| 48 | # Process operations |
| 49 | while position < len(tokens): |
| 50 | # Check for valid operations |
| 51 | op = tokens[position] |
| 52 | position += 1 |
| 53 | |
| 54 | # Handle two-word operations |
| 55 | if op == "multiplied" or op == "divided": |
| 56 | if position >= len(tokens): |
| 57 | raise ValueError("syntax error") |
| 58 | |
| 59 | if op == "multiplied" and tokens[position] == "by": |
| 60 | op = "multiplied by" |
| 61 | position += 1 |
| 62 | elif op == "divided" and tokens[position] == "by": |
| 63 | op = "divided by" |
| 64 | position += 1 |
| 65 | else: |
| 66 | # Unknown operation |
| 67 | raise ValueError("unknown operation") |
| 68 | elif op not in ["plus", "minus"]: |
| 69 | # Unknown single-word operation |
| 70 | raise ValueError("unknown operation") |
| 71 | |
| 72 | # Edge Case: Missing number after operation |
| 73 | if position >= len(tokens): |
| 74 | raise ValueError("syntax error") |
| 75 | |
| 76 | # Parse next number |
| 77 | try: |
| 78 | num = int(tokens[position]) |
| 79 | except ValueError: |
| 80 | # Edge Case: Token after operation is not a number |
| 81 | # Check if this is an unknown operation |
| 82 | if tokens[position] not in ["plus", "minus", "multiplied", "divided"]: |
| 83 | # This is not a number and not a known operation - check if it's an unknown operation |
| 84 | if position + 1 < len(tokens) and tokens[position + 1] == "by": |
| 85 | # This looks like an unknown two-word operation |
| 86 | raise ValueError("unknown operation") |
| 87 | else: |
| 88 | # This is an unknown single-word operation |
| 89 | raise ValueError("unknown operation") |
| 90 | else: |
| 91 | # This is a known operation but we're missing a number |
| 92 | raise ValueError("syntax error") |
| 93 | |
| 94 | # Perform operation |
| 95 | if op == "plus": |
| 96 | result += num |
| 97 | elif op == "minus": |
| 98 | result -= num |
| 99 | elif op == "multiplied by": |
| 100 | result *= num |
| 101 | elif op == "divided by": |
| 102 | # Edge Case: Division by zero |
| 103 | if num == 0: |
| 104 | raise ValueError("syntax error") |
| 105 | result //= num |
| 106 | else: |
| 107 | # Edge Case: Unknown operation |
| 108 | raise ValueError("unknown operation") |
| 109 | |
| 110 | position += 1 |
| 111 | |
| 112 | return result |