這篇文章將為大家詳細講解有關(guān)Python怎么實現(xiàn)棧,小編覺得挺實用的,因此分享給大家做個參考,希望大家閱讀完這篇文章后可以有所收獲。
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兩種實現(xiàn)方式:
基于數(shù)組 - 數(shù)組同時基于鏈表實現(xiàn)
基于單鏈表 - 單鏈表的節(jié)點時一個實例化的node 對象
完整代碼可見GitHub:
https://github.com/GYT0313/Python-DataStructure/tree/master/5-stack
目錄結(jié)構(gòu):
注:一個完整的代碼并不是使用一個py文件,而使用了多個文件通過繼承方式實現(xiàn)。
arraycollection.py
""" File: abstractcollection.py Author: Ken Lambert """ class AbstractCollection(object): """An abstract collection implementation.""" # Constructor def __init__(self, sourceCollection = None): """Sets the initial state of self, which includes the contents of sourceCollection, if it's present.""" self._size = 0 if sourceCollection: for item in sourceCollection: self.add(item) # Accessor methods def isEmpty(self): """Returns True if len(self) == 0, or False otherwise.""" return len(self) == 0 def __len__(self): """Returns the number of items in self.""" return self._size def __str__(self): """Returns the string representation of self.""" return "[" + ", ".join(map(str, self)) + "]" def __add__(self, other): """Returns a new bag containing the contents of self and other.""" result = type(self)(self) for item in other: result.add(item) return result def __eq__(self, other): """Returns True if self equals other, or False otherwise.""" if self is other: return True if type(self) != type(other) or \ len(self) != len(other): return False otherIter = iter(other) for item in self: if item != next(otherIter): return False return True
abstractstack.py
""" File: abstractstack.py Author: Ken Lambert """ from abstractcollection import AbstractCollection class AbstractStack(AbstractCollection): """An abstract stack implementation.""" # Constructor def __init__(self, sourceCollection = None): """Sets the initial state of self, which includes the contents of sourceCollection, if it's present.""" AbstractCollection.__init__(self, sourceCollection) # Mutator methods def add(self, item): """Adds item to self.""" self.push(item)2. 基于數(shù)組
運行示例:
代碼:
棧實現(xiàn):arraystack.py
""" File: abstractstack.py Author: Ken Lambert """ from abstractcollection import AbstractCollection class AbstractStack(AbstractCollection): """An abstract stack implementation.""" # Constructor def __init__(self, sourceCollection = None): """Sets the initial state of self, which includes the contents of sourceCollection, if it's present.""" AbstractCollection.__init__(self, sourceCollection) # Mutator methods def add(self, item): """Adds item to self.""" self.push(item)
數(shù)組實現(xiàn):arrays.py
""" File: arrays.py An Array is a restricted list whose clients can use only [], len, iter, and str. To instantiate, use3. 基于鏈表= array( , ) The fill value is None by default. """ class Array(object): """Represents an array.""" def __init__(self, capacity, fillValue = None): """Capacity is the static size of the array. fillValue is placed at each position.""" self._items = list() for count in range(capacity): self._items.append(fillValue) def __len__(self): """-> The capacity of the array.""" return len(self._items) def __str__(self): """-> The string representation of the array.""" return str(self._items) def __iter__(self): """Supports iteration over a view of an array.""" return iter(self._items) def __getitem__(self, index): """Subscript operator for access at index.""" return self._items[index] def __setitem__(self, index, newItem): """Subscript operator for replacement at index.""" self._items[index] = newItem
運行示例:
代碼:
linkedstack.py
""" linkedstack.py """ from node import Node from abstractstack import AbstractStack class LinkedStack(AbstractStack): """基于單鏈表實現(xiàn)棧-鏈表頭部為棧頂""" def __init__(self, source_collection=None): self._items = None AbstractStack.__init__(self, source_collection) def __iter__(self): """迭代-使用一個列表實現(xiàn), 列表第一項為單鏈表的最后一項""" def visit_nodes(node): if node != None: visit_nodes(node.next) temp_list.append(node.data) temp_list = [] visit_nodes(self._items) return iter(temp_list) def peek(self): """返回棧頂元素""" self._prior_condition() return self._items.data def clear(self): """清空列表""" self._size = 0 self._items = None def push(self, item): """入棧""" self._items = Node(item, self._items) self._size += 1 def pop(self): """出棧""" self._prior_condition() old_item = self._items.data self._items = self._items.next self._size -= 1 return old_item def _prior_condition(self): if self._size == 0: raise KeyError("The stack is empty.")
node.py
""" 鏈表結(jié)構(gòu)的節(jié)點類 """ class Node(object): def __init__(self, data, next=None): self.data = data self.next = next
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