Python链表与反链表

# -*- coding:utf8 -*-
#/usr/bin/env python

class Node(object):
    def __init__(self, data, pnext = None):
        self.data = data
        self._next = pnext
        print('self._next',self._next)

    def __repr__(self):
        return str(self.data)

class ChainTable(object):
    def __init__(self):
        self.head = None
        self.length = 0

    def isEmpty(self):
        return (self.length == 0)

    def append(self, dataOrNode):
        item = None
        print('Node',Node)
        if isinstance(dataOrNode, Node):
            item = dataOrNode
            print(123)
        else:
            item = Node(dataOrNode)
            print(item,456)
        if not self.head:
            self.head = item
            self.length += 1
            print('self.head',self.head._next)
        else:
            node = self.head
            print('1111node',node)
            print('111node._next',node._next)
            while node._next:
                print(222222222222222222222222,node._next)
                node = node._next
                print(444444444444444,node)
            node._next = item
            print(11111111111111111111111,node._next)
            self.length += 1

    def reverseChainTable(self,chaintable):
        if isinstance(chaintable, Node):
            item = chaintable
            print(123)
        else:
            print('这不是链表')
            return


    def delete(self, index):
        if self.isEmpty():
            print ("this chain table is empty.")
            return

        if index < 0 or index >= self.length:
            print ('error: out of index')
            return

        if index == 0:
            self.head = self.head._next
            self.length -= 1
            return

        j = 0
        node = self.head
        prev = self.head
        while node._next and j < index:
            prev = node
            node = node._next
            j += 1

        if j == index:
            prev._next = node._next
            self.length -= 1

    def insert(self, index, dataOrNode):
        if self.isEmpty():
            print ("this chain tabale is empty")
            return

        if index < 0 or index >= self.length:
            print ("error: out of index")
            return

        item = None
        if isinstance(dataOrNode, Node):
            item = dataOrNode
        else:
            item = Node(dataOrNode)

        if index == 0:
            item._next = self.head
            self.head = item
            self.length += 1
            return

        j = 0
        node = self.head
        prev = self.head
        while node._next and j < index:
            prev = node
            node = node._next
            j += 1

        if j == index:
            item._next = node
            prev._next = item
            self.length += 1

    def update(self, index, data):
        if self.isEmpty() or index < 0 or index >= self.length:
            print ('error: out of index')
            return
        j = 0
        node = self.head
        while node._next and j < index:
            node = node._next
            j += 1

        if j == index:
            node.data = data

    def getItem(self, index):
        if self.isEmpty() or index < 0 or index >= self.length:
            print ("error: out of index")
            return
        j = 0
        node = self.head
        while node._next and j < index:
            node = node._next
            j += 1

        return node.data


    def getIndex(self, data):
        j = 0
        if self.isEmpty():
            print ("this chain table is empty")
            return
        node = self.head
        while node:
            if node.data == data:
                return j
            node = node._next
            j += 1

        if j == self.length:
            print ("%s not found" % str(data))
            return

    def clear(self):
        self.head = None
        self.length = 0

    def __repr__(self):
        if self.isEmpty():
            return "empty chain table"
        node = self.head
        nlist = ''
        while node:
            nlist += str(node.data) + ' '
            node = node._next
        return nlist

    def __getitem__(self, ind):
        if self.isEmpty() or ind < 0 or ind >= self.length:
            print ("error: out of index")
            return
        return self.getItem(ind)

    def __setitem__(self, ind, val):
        if self.isEmpty() or ind < 0 or ind >= self.length:
            print ("error: out of index")
            return
        self.update(ind, val)

    def __len__(self):
        return self.length

chariin = ChainTable()
for i in range(10):
    chariin.append(i)

print(chariin)

从哪里找的忘了，不过思路已经整的很明白了

下面是链表翻转的：

来源 https://blog.csdn.net/u011608357/article/details/36933337

单链表的反转可以使用循环，也可以使用递归的方式

1.循环反转单链表

循环的方法中，使用pre指向前一个结点，cur指向当前结点，每次把cur->next指向pre即可。

    

class ListNode:
    def __init__(self,x):
        self.val=x;
        self.next=None;
 
def nonrecurse(head):              #循环的方法反转链表
    if head is None or head.next is None:
        return head;
    pre=None;
    cur=head;
    h=head;
    while cur:
        h=cur;
        tmp=cur.next;
        cur.next=pre;
        pre=cur;
        cur=tmp;
    return h;
    
head=ListNode(1);    #测试代码
p1=ListNode(2);      #建立链表1->2->3->4->None;
p2=ListNode(3);
p3=ListNode(4);
head.next=p1;
p1.next=p2;
p2.next=p3;
p=nonrecurse(head);   #输出链表 4->3->2->1->None
while p:
    print p.val;
    p=p.next;

反转代码：

class ListNode:
    def __init__(self,x):
        self.val=x;
        self.next=None;
 
    
def recurse(head,newhead):    #递归，head为原链表的头结点，newhead为反转后链表的头结点
    if head is None:
        return ;
    if head.next is None:
        newhead=head;
    else :
        newhead=recurse(head.next,newhead);
        head.next.next=head;
        head.next=None;
    return newhead;
    
head=ListNode(1);               #测试代码
p1=ListNode(2);                 # 建立链表1->2->3->4->None
p2=ListNode(3);
p3=ListNode(4);
head.next=p1;
p1.next=p2;
p2.next=p3;
newhead=None;
p=recurse(head,newhead);           #输出链表4->3->2->1->None
while p:
    print p.val;
    p=p.next;