python实现之极简stack和queue

用python实现一个极简的stack和queue，那是so easy的事情了，简洁易懂，适合小白~

直接上代码吧：

node:

class LinkNode:
    def __init__( self, value ):
        self.value = value
        self.next = None

stack:

class Stack:
    def __init__( self ):
        self.top = None

    def peek( self ):
        if not self.top:
            return None
        return self.top.value

    def is_empty( self ):
        return self.top == None

    def pop( self ):
        if not self.top:
            return None
        old_top = self.top
        self.top = self.top.next
        return old_top.value

    def push( self, value ):
        node = LinkNode( value )
        node.next = self.top
        self.top = node

queue:

class Queue:
    def __init__( self ):
        self.first = None
        self.last = None

    def is_empty( self ):
        return self.last == None

    def dequeue( self ):
        if not self.first:
            return None
        old_first = self.first
        self.first = self.first.next
        if not self.first:
            self.last = None
        return old_first.value

    def enqueue( self, value ):
        node = LinkNode( value )
        if not self.last:
            self.first = node
            self.last = node
        else:
            self.last.next = node
            self.last = node

test case:

# '''
    # Stack test case
    # '''
    s = Stack()
    s.push( 1 )
    s.push( 0 )
    s.push( -1 )
    s.push( -1 )
    s.push( 6 )
    print( s.peek() )
    s.pop()
    print( s.peek() )

    s.pop()
    s.pop()
    s.pop()
    print( s.peek() )

    s.pop()
    print( s.top )

    # '''
    # Queue test case
    # '''
    q = Queue()
    q.enqueue( 1 )
    q.enqueue( 2 )
    q.enqueue( 0 )
    q.enqueue( -1 )
    q.enqueue( 8 )
    q.dequeue()
    q.dequeue()
    q.dequeue()
    q.dequeue()
    print( q.first.value )