-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathstack.py
More file actions
115 lines (90 loc) · 2.56 KB
/
Copy pathstack.py
File metadata and controls
115 lines (90 loc) · 2.56 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
"""
Stack Abstract Data Type (ADT)
"""
from abc import ABC, ABCMeta, abstractmethod
class AbstractStack(metaclass=ABCMeta):
"""Abstract Class for Stacks."""
def __init__(self):
self._top = -1
def __len__(self):
return self._top + 1
def __str__(self):
result = " ".join(map(str, self))
return 'Top-> ' + result
def is_empty(self):
return self._top == -1
@abstractmethod
def __iter__(self):
pass
@abstractmethod
def push(self, value):
pass
@abstractmethod
def pop(self):
pass
@abstractmethod
def peek(self):
pass
class ArrayStack(AbstractStack):
def __init__(self, size: int = 10):
super(ArrayStack, self).__init__()
self._stack: list = [None] * size
def __iter__(self):
st_idx = self._top
while True:
if st_idx == -1:
break
yield self._stack[st_idx]
st_idx -= 1
def push(self, value):
self._top += 1
if self._top == len(self._stack):
self._expand()
self._stack[self._top] = value
def pop(self):
if self.is_empty():
raise IndexError("ArrayStack empty!")
val = self._stack[self._top]
self._stack[self._top] = None # 清除当前栈的元素
self._top -= 1
return val
def peek(self):
# 返回栈顶元素
if self.is_empty():
raise IndexError("ArrayStack empty!")
return self._stack[self._top]
def _expand(self):
# 扩容
self._stack += [None] * len(self._stack)
class Node(object):
def __init__(self, val):
self.val = val
self.next = None
class LinkedListStack(AbstractStack, ABC):
# 使用单链表构建的栈，头插法
def __init__(self):
super(LinkedListStack, self).__init__()
self._head: Node = None
def __iter__(self):
st_head = self._head
while st_head:
yield st_head.val
st_head = st_head.next
def push(self, value):
node = Node(value)
# if self._head:
# node.next = self._head
node.next = self._head
self._head = node
self._top += 1
def pop(self):
if self.is_empty():
raise IndexError("LinkedListStack empty")
val = self._head.val
self._head = self._head.next
self._top -= 1
return val
def peek(self):
if self.is_empty():
raise IndexError("LinkedListStack empty")
return self._head.val