| 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" and "?" from the question |
| 11 | question = question[8:-1].strip() |
| 12 | |
| 13 | # Edge Case: Question is just "What is?" with no content |
| 14 | if not question: |
| 15 | raise ValueError("syntax error") |
| 16 | |
| 17 | # Define word to operator mappings |
| 18 | operators = { |
| 19 | "plus": "+", |
| 20 | "minus": "-", |
| 21 | "multiplied": "*", |
| 22 | "divided": "/" |
| 23 | } |
| 24 | |
| 25 | # Tokenize the question |
| 26 | tokens = question.split() |
| 27 | |
| 28 | # Edge Case: Invalid syntax with no tokens |
| 29 | if not tokens: |
| 30 | raise ValueError("syntax error") |
| 31 | |
| 32 | # Parse tokens into numbers and operators |
| 33 | parsed_tokens = [] |
| 34 | i = 0 |
| 35 | while i < len(tokens): |
| 36 | token = tokens[i] |
| 37 | |
| 38 | # Try to parse as number |
| 39 | try: |
| 40 | num = int(token) |
| 41 | parsed_tokens.append(num) |
| 42 | i += 1 |
| 43 | continue |
| 44 | except ValueError: |
| 45 | pass |
| 46 | |
| 47 | # Handle operators |
| 48 | if token in operators: |
| 49 | # Special handling for "multiplied by" and "divided by" |
| 50 | if token == "multiplied" or token == "divided": |
| 51 | # Edge Case: Incomplete "multiplied" or "divided" operation |
| 52 | if i + 1 >= len(tokens): |
| 53 | raise ValueError("syntax error") |
| 54 | |
| 55 | next_token = tokens[i + 1] |
| 56 | if (token == "multiplied" and next_token != "by") or \ |
| 57 | (token == "divided" and next_token != "by"): |
| 58 | raise ValueError("syntax error") |
| 59 | |
| 60 | parsed_tokens.append(operators[token]) |
| 61 | i += 2 |
| 62 | continue |
| 63 | else: |
| 64 | parsed_tokens.append(operators[token]) |
| 65 | i += 1 |
| 66 | continue |
| 67 | |
| 68 | # Edge Case: Unknown operation |
| 69 | raise ValueError("unknown operation") |
| 70 | |
| 71 | # Edge Case: Invalid syntax - operator at the end |
| 72 | if len(parsed_tokens) > 0 and isinstance(parsed_tokens[-1], str): |
| 73 | raise ValueError("syntax error") |
| 74 | |
| 75 | # Edge Case: Invalid syntax - number at the beginning followed by number |
| 76 | for i in range(len(parsed_tokens) - 1): |
| 77 | if isinstance(parsed_tokens[i], int) and isinstance(parsed_tokens[i + 1], int): |
| 78 | raise ValueError("syntax error") |
| 79 | |
| 80 | # Edge Case: Invalid syntax - operator followed by operator |
| 81 | for i in range(len(parsed_tokens) - 1): |
| 82 | if isinstance(parsed_tokens[i], str) and isinstance(parsed_tokens[i + 1], str): |
| 83 | raise ValueError("syntax error") |
| 84 | |
| 85 | # Evaluate the expression from left to right |
| 86 | # Edge Case: Single number |
| 87 | if len(parsed_tokens) == 1 and isinstance(parsed_tokens[0], int): |
| 88 | return parsed_tokens[0] |
| 89 | |
| 90 | # Edge Case: Invalid syntax - incorrect number of tokens |
| 91 | if len(parsed_tokens) < 3 or len(parsed_tokens) % 2 == 0: |
| 92 | raise ValueError("syntax error") |
| 93 | |
| 94 | result = parsed_tokens[0] |
| 95 | i = 1 |
| 96 | while i < len(parsed_tokens): |
| 97 | operator = parsed_tokens[i] |
| 98 | # Edge Case: Missing operand |
| 99 | if i + 1 >= len(parsed_tokens): |
| 100 | raise ValueError("syntax error") |
| 101 | |
| 102 | operand = parsed_tokens[i + 1] |
| 103 | |
| 104 | if operator == "+": |
| 105 | result += operand |
| 106 | elif operator == "-": |
| 107 | result -= operand |
| 108 | elif operator == "*": |
| 109 | result *= operand |
| 110 | elif operator == "/": |
| 111 | # Edge Case: Division by zero |
| 112 | if operand == 0: |
| 113 | raise ValueError("syntax error") # Following test expectations |
| 114 | result //= operand # Integer division as per examples |
| 115 | else: |
| 116 | # Edge Case: Unknown operator in evaluation |
| 117 | raise ValueError("unknown operation") |
| 118 | |
| 119 | i += 2 |
| 120 | |
| 121 | return result |
| 122 | # Handled Edge Cases: Empty input, None input, questions not starting with "What is", questions with no content after "What is", invalid syntax with no tokens, unknown operations, incomplete "multiplied/divided" operations, operators at the end, numbers followed by numbers, operators followed by operators, single number, incorrect number of tokens, missing operands, division by zero, unknown operators during evaluation |