python栈的实现和应用

秉着不重复造轮子，栈stack可从pythonds3包中导入，其具体的实现如下：

class Stack:
    """Stack implementation as a list"""

    def __init__(self):
        """Create new stack"""
        self._items = []

    def is_empty(self):
        """Check if the stack is empty"""
        return not bool(self._items)

    def push(self, item):
        """Add an item to the stack"""
        self._items.append(item)

    def pop(self):
        """Remove an item from the stack"""
        return self._items.pop()

    def peek(self):
        """Get the value of the top item in the stack"""
        return self._items[-1]

    def size(self):
        """Get the number of items in the stack"""
        return len(self._items)

Stack

1.简单括号匹配

如：(())、((()) 括号组的检测

from pythonds3.basic import Stack


def par_checker(symbol_string):
    s = Stack()
    for symbol in symbol_string:
        if symbol == '(':
            s.push(symbol)
        elif s.is_empty():
            return False
        else:
            s.pop()
    if s.is_empty():
        return True
    else:
        return False

2.括号匹配

from pythonds3.basic import Stack

OPENS = '([{'
CLOSERS = ')]}'


def par_checker(symbol_string):
    s = Stack()
    for symbol in symbol_string:
        if symbol in OPENS:
            s.push(symbol)
        elif s.is_empty():
            return False
        else:
            top = s.pop()
            if not match(top, symbol):
                return False
    if s.is_empty():
        return True
    else:
        return False


def match(op, cl):
    return OPENS.index(op) == CLOSERS.index(cl)

3.十进制转换为任意进制

from pythonds3.basic.stack import Stack


def base_converter(dec_number, base):
    digits = '0123456789ABCDEF'
    rem_stack = Stack()
    while dec_number > 0:
        rem = dec_number % base
        rem_stack.push(rem)
        dec_number = dec_number // base
    num_string = ''
    while not rem_stack.is_empty():
        num_string = num_string + digits[rem_stack.pop()]

    return num_string

python栈的实现和应用

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