基于Python程序,用列表与栈配合求表达式的值{ [ (2+3)×5 ]-7×8 }×3
时间: 2024-12-18 15:23:42 浏览: 6
在Python中,你可以使用列表(list)来模拟操作数堆栈(stack),结合栈数据结构来解析和计算给定的嵌套表达式。首先,我们需要创建一个函数来处理这种类型的表达式。这里我们可以利用递归和栈来逐步解析和计算:
```python
def evaluate(expression):
def apply_operator(operators, values):
op = operators.pop()
right = values.pop()
left = values.pop()
if op == '+':
values.append(left + right)
elif op == '-':
values.append(left - right)
elif op == '*':
values.append(left * right)
else:
values.append(left / right)
def greater_precedence(op1, op2):
precedence = {'*': 2, '/': 2, '+': 1, '-': 1}
return precedence[op1] > precedence[op2]
operators = []
values = []
i = 0
while i < len(expression):
if expression[i].isdigit():
num = ''
while i < len(expression) and expression[i].isdigit():
num += expression[i]
i += 1
values.append(int(num))
elif expression[i] in ['(', ')']:
operators.append(expression[i])
elif expression[i] in ['+', '-', '*', '/']:
while (operators and operators[-1] != '(' and
greater_precedence(operators[-1], expression[i])):
apply_operator(operators, values)
operators.append(expression[i])
i += 1
# Process the remaining operators
while operators:
apply_operator(operators, values)
# Handle the final result
return values[0] if operators[-1] == ')' else None
# 测试表达式
expression = "[(2+3)*5]-7*8"
result = evaluate(expression.replace(" ", ""))
print(f"表达式的值为: {result}")
#
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