| 1 | 1 | def answer(question): |
| 2 | | pass |
| 2 | # Edge Case: Empty or null input strings |
| 3 | if not question: |
| 4 | raise ValueError("syntax error") |
| 5 | |
| 6 | # Check if the question starts with "What is" |
| 7 | if not question.startswith("What is"): |
| 8 | raise ValueError("unknown operation") |
| 9 | |
| 10 | # Remove "What is" and the trailing question mark |
| 11 | question = question[8:-1].strip() |
| 12 | |
| 13 | # Edge Case: Non-math questions or empty expression after "What is" |
| 14 | if not question: |
| 15 | raise ValueError("syntax error") |
| 16 | |
| 17 | # Replace word operations with symbols |
| 18 | question = question.replace("plus", "+") |
| 19 | question = question.replace("minus", "-") |
| 20 | question = question.replace("multiplied by", "*") |
| 21 | question = question.replace("divided by", "/") |
| 22 | |
| 23 | # Split the question into tokens |
| 24 | tokens = question.split() |
| 25 | |
| 26 | # Edge Case: Invalid syntax with no numbers |
| 27 | if not tokens: |
| 28 | raise ValueError("syntax error") |
| 29 | |
| 30 | # Parse the tokens |
| 31 | equation = [] |
| 32 | i = 0 |
| 33 | while i < len(tokens): |
| 34 | token = tokens[i] |
| 35 | if token in "+-*/": |
| 36 | equation.append(token) |
| 37 | else: |
| 38 | # Try to convert to integer |
| 39 | try: |
| 40 | num = int(token) |
| 41 | equation.append(num) |
| 42 | except ValueError: |
| 43 | # Edge Case: Unsupported operations or non-mathematical words |
| 44 | raise ValueError("unknown operation") |
| 45 | i += 1 |
| 46 | |
| 47 | # Edge Case: Missing operands or operators |
| 48 | if len(equation) == 0: |
| 49 | raise ValueError("syntax error") |
| 50 | |
| 51 | # Edge Case: Expression starting with an operator |
| 52 | if isinstance(equation[0], str) and equation[0] in "+-*/": |
| 53 | raise ValueError("syntax error") |
| 54 | |
| 55 | # Edge Case: Consecutive operators without operands |
| 56 | for i in range(len(equation) - 1): |
| 57 | if isinstance(equation[i], str) and equation[i] in "+-*/": |
| 58 | if isinstance(equation[i+1], str) and equation[i+1] in "+-*/": |
| 59 | raise ValueError("syntax error") |
| 60 | |
| 61 | # Edge Case: Expression ending with an operator |
| 62 | if isinstance(equation[-1], str) and equation[-1] in "+-*/": |
| 63 | raise ValueError("syntax error") |
| 64 | |
| 65 | # Evaluate the expression from left to right |
| 66 | while len(equation) > 1: |
| 67 | try: |
| 68 | # Edge Case: Invalid syntax during evaluation |
| 69 | if len(equation) < 3: |
| 70 | raise ValueError("syntax error") |
| 71 | |
| 72 | x_value, operation, y_value, *rest = equation |
| 73 | |
| 74 | # Edge Case: Non-numeric operands |
| 75 | if not isinstance(x_value, int) or not isinstance(y_value, int): |
| 76 | raise ValueError("syntax error") |
| 77 | |
| 78 | # Edge Case: Non-operator in operation position |
| 79 | if operation not in "+-*/": |
| 80 | raise ValueError("syntax error") |
| 81 | |
| 82 | if operation == "+": |
| 83 | result = x_value + y_value |
| 84 | elif operation == "-": |
| 85 | result = x_value - y_value |
| 86 | elif operation == "*": |
| 87 | result = x_value * y_value |
| 88 | elif operation == "/": |
| 89 | # Edge Case: Division by zero |
| 90 | if y_value == 0: |
| 91 | raise ValueError("syntax error") |
| 92 | result = x_value // y_value # Integer division as per examples |
| 93 | |
| 94 | equation = [result] + rest |
| 95 | except ValueError: |
| 96 | # Re-raise with syntax error message |
| 97 | raise ValueError("syntax error") |
| 98 | except: |
| 99 | # Edge Case: Any other evaluation errors |
| 100 | raise ValueError("syntax error") |
| 101 | |
| 102 | # Edge Case: Final result is not a number |
| 103 | if not isinstance(equation[0], int): |
| 104 | raise ValueError("syntax error") |
| 105 | |
| 106 | return equation[0] |
| 107 | # Handled Edge Cases: Empty or null input strings, Non-math questions, Invalid syntax with no numbers, Unsupported operations, Missing operands or operators, Expression starting with an operator, Consecutive operators without operands, Expression ending with an operator, Non-numeric operands, Non-operator in operation position, Division by zero, Any other evaluation errors, Final result is not a number |