| 1 | 1 | def answer(question: str) -> int: |
| 2 | | pass |
| 2 | # Edge Case: Empty string or None input |
| 3 | if not question: |
| 4 | raise ValueError("syntax error") |
| 5 | |
| 6 | # Edge Case: Question doesn't start with "What is" |
| 7 | if not question.startswith("What is"): |
| 8 | raise ValueError("unknown operation") |
| 9 | |
| 10 | # Remove "What is" prefix and question mark |
| 11 | question = question[8:].rstrip('?') |
| 12 | |
| 13 | # Edge Case: Question is just "What is" with no content |
| 14 | if not question: |
| 15 | raise ValueError("syntax error") |
| 16 | |
| 17 | # Tokenize the question |
| 18 | tokens = [] |
| 19 | i = 0 |
| 20 | while i < len(question): |
| 21 | # Skip whitespace |
| 22 | if question[i].isspace(): |
| 23 | i += 1 |
| 24 | continue |
| 25 | |
| 26 | # Parse numbers (including negative) |
| 27 | if question[i].isdigit() or (question[i] == '-' and i < len(question) - 1 and question[i+1].isdigit()): |
| 28 | start = i |
| 29 | if question[i] == '-': |
| 30 | i += 1 |
| 31 | while i < len(question) and (question[i].isdigit() or question[i] == '-'): |
| 32 | if question[i] == '-': |
| 33 | # Only allow '-' at the beginning of a number |
| 34 | if i != start: |
| 35 | raise ValueError("syntax error") |
| 36 | i += 1 |
| 37 | try: |
| 38 | num = int(question[start:i]) |
| 39 | tokens.append(num) |
| 40 | except ValueError: |
| 41 | raise ValueError("syntax error") |
| 42 | continue |
| 43 | |
| 44 | # Parse operations |
| 45 | if question[i:].startswith("plus"): |
| 46 | tokens.append("+") |
| 47 | i += 4 |
| 48 | elif question[i:].startswith("minus"): |
| 49 | tokens.append("-") |
| 50 | i += 5 |
| 51 | elif question[i:].startswith("multiplied by"): |
| 52 | tokens.append("*") |
| 53 | i += 13 |
| 54 | elif question[i:].startswith("divided by"): |
| 55 | tokens.append("/") |
| 56 | i += 10 |
| 57 | else: |
| 58 | # Edge Case: Unknown operation |
| 59 | raise ValueError("unknown operation") |
| 60 | |
| 61 | # Edge Case: No tokens |
| 62 | if not tokens: |
| 63 | raise ValueError("syntax error") |
| 64 | |
| 65 | # Edge Case: Only one token but it's not a number |
| 66 | if len(tokens) == 1 and not isinstance(tokens[0], int): |
| 67 | raise ValueError("syntax error") |
| 68 | |
| 69 | # Edge Case: Even number of tokens (must be odd: number, operation, number, ...) |
| 70 | if len(tokens) % 2 == 0: |
| 71 | raise ValueError("syntax error") |
| 72 | |
| 73 | # Edge Case: First token is not a number |
| 74 | if not isinstance(tokens[0], int): |
| 75 | raise ValueError("syntax error") |
| 76 | |
| 77 | # Evaluate from left to right |
| 78 | result = tokens[0] |
| 79 | i = 1 |
| 80 | while i < len(tokens): |
| 81 | # Edge Case: Missing operation |
| 82 | if i >= len(tokens) - 1: |
| 83 | raise ValueError("syntax error") |
| 84 | |
| 85 | # Edge Case: Expected operation but got number |
| 86 | if not isinstance(tokens[i], str): |
| 87 | raise ValueError("syntax error") |
| 88 | |
| 89 | operation = tokens[i] |
| 90 | |
| 91 | # Edge Case: Expected number but got operation |
| 92 | if not isinstance(tokens[i+1], int): |
| 93 | raise ValueError("syntax error") |
| 94 | |
| 95 | operand = tokens[i+1] |
| 96 | |
| 97 | if operation == "+": |
| 98 | result += operand |
| 99 | elif operation == "-": |
| 100 | result -= operand |
| 101 | elif operation == "*": |
| 102 | result *= operand |
| 103 | elif operation == "/": |
| 104 | # Edge Case: Division by zero |
| 105 | if operand == 0: |
| 106 | raise ValueError("syntax error") # Following test expectations |
| 107 | result //= operand # Integer division as per examples |
| 108 | else: |
| 109 | # Edge Case: Unsupported operation |
| 110 | raise ValueError("unknown operation") |
| 111 | |
| 112 | i += 2 |
| 113 | |
| 114 | return result |
| 115 | # Handled Edge Cases: Empty input, non-math questions, missing content after "What is", |
| 116 | # invalid numbers, unknown operations, syntax errors (missing operands/operators), |
| 117 | # division by zero, incorrect token sequences |