跟栈有关,但是吧,感觉又做不对,做一点就不会了,也不知道正确答案
【以下回答由 GPT 生成】
顺序栈是线性数据结构,具有"先进后出"的特性。在实际应用中,顺序栈可以被广泛应用于许多场景,例如表达式求值、括号匹配、撤销操作、浏览器的前进后退功能等。
首先,我们需要创建一个顺序栈。顺序栈可以由数组实现,需要定义一个数组和一个指向栈顶的指针。
class Stack:
def __init__(self, capacity):
self.capacity = capacity # 栈的容量
self.stack = [None] * capacity # 用于存放栈元素的数组
self.top = -1 # 栈顶指针初始化为-1
def is_empty(self):
return self.top == -1 # 当栈顶指针为-1时,表示栈为空
def is_full(self):
return self.top == self.capacity - 1 # 当栈顶指针等于栈容量减1时,表示栈已满
def push(self, item):
if self.is_full():
raise Exception("Stack is full")
self.top += 1
self.stack[self.top] = item # 将元素添加到栈顶
def pop(self):
if self.is_empty():
raise Exception("Stack is empty")
item = self.stack[self.top] # 获取栈顶元素
self.top -= 1
return item
def peek(self):
if self.is_empty():
raise Exception("Stack is empty")
return self.stack[self.top] # 获取栈顶元素,但不删除
顺序栈可以用于实现表达式求值。通过将中缀表达式转换为后缀表达式,然后使用栈进行运算。
def evaluate_postfix(postfix_expression):
stack = Stack(len(postfix_expression))
for token in postfix_expression:
if token.isdigit():
stack.push(int(token))
else:
operand2 = stack.pop()
operand1 = stack.pop()
result = evaluate_expression(token, operand1, operand2)
stack.push(result)
return stack.pop()
def evaluate_expression(operator, operand1, operand2):
if operator == "+":
return operand1 + operand2
elif operator == "-":
return operand1 - operand2
elif operator == "*":
return operand1 * operand2
elif operator == "/":
return operand1 / operand2
顺序栈可以用于实现括号匹配。通过遍历字符串,将左括号入栈,遇到右括号时出栈与当前右括号进行匹配。
def is_parentheses_matching(expression):
stack = Stack(len(expression))
for char in expression:
if char in "([{":
stack.push(char)
elif char in ")]}":
if stack.is_empty() or not is_matching(stack.peek(), char):
return False
stack.pop()
return stack.is_empty()
def is_matching(left, right):
if (left == "(" and right == ")") or \
(left == "[" and right == "]") or \
(left == "{" and right == "}"):
return True
else:
return False
顺序栈可以用于实现撤销操作。每次进行操作时,将操作记录入栈,当需要撤销时,从栈中取出最近一次的操作进行反向操作。
class TextEditor:
def __init__(self):
self.content = ""
self.operation_stack = Stack(100)
def insert_text(self, text):
self.content += text
self.operation_stack.push(("delete_text", len(text)))
def delete_text(self, length):
if length > len(self.content):
raise Exception("Invalid delete operation")
self.content = self.content[:-length]
self.operation_stack.push(("insert_text", self.content[-length:]))
def undo(self):
if self.operation_stack.is_empty():
raise Exception("No operation to undo")
operation, data = self.operation_stack.pop()
if operation == "delete_text":
self.content += data
elif operation == "insert_text":
self.content = self.content[:-data]
顺序栈可以用于实现浏览器的前进后退功能。通过将浏览的网页链接记录在栈中,当点击后退按钮时,从栈中取出上一个链接,当点击前进按钮时,从栈中取出下一个链接。
class Browser:
def __init__(self):
self.back_stack = Stack(100)
self.forward_stack = Stack(100)
def visit_page(self, page):
self.back_stack.push(page)
self.forward_stack = Stack(100) # 清空前进栈
def go_back(self):
if self.back_stack.is_empty():
raise Exception("No page to go back")
current_page = self.back_stack.pop()
self.forward_stack.push(current_page)
def go_forward(self):
if self.forward_stack.is_empty():
raise Exception("No page to go forward")
current_page = self.forward_stack.pop()
self.back_stack.push(current_page)
顺序栈在数据结构中应用广泛,以上列举了其中几个常见的应用场景,并给出了具体的解决方案。在实际使用中,可以根据具体需求进行适当的修改和扩展。如果还有其他问题,欢迎继续提问。
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