python 链表(带头节点和不带)

最新推荐文章于 2023-09-12 18:07:10 发布

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本文深入探讨了链表的实现和操作，包括带头节点和不带头节点的链表创建、插入、删除、遍历、反转及判空等核心功能。通过具体代码示例，详细解析了链表的内部机制和算法实现。

一：带头节点，用了一个类包装

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

# 链表 带头节点方便第一个元素的插入和删除
class LinkedList:
    def __init__(self):
        # 初始化为空表
        self.head = None

    # 建表
    def creatList(self, n):
        self.head = Node()
        p = self.head
        for i in range(n):
            node = Node()
            node.data = int(input())
            p.next = node
            p = p.next
        p.next = None

    #在第n个位置插入value
    def insert(self, n, value):
        p = self.head
        if n > self.length():
            return 0
        while n and p.next:
            n -= 1
            p = p.next

        node = Node()
        node.data = value
        node.next = p.next
        p.next = node

    # 删除第n个元素
    def remove(self, n):
        p = self.head
        if n > self.length():
            return 0
        n -= 1
        while n and p.next:
            n -= 1
            p = p.next

        p.next = p.next.next        

    def traveList(self):
        p = self.head.next
        while p:
            print(p.data, ' ', end='')
            p = p.next
        print()

    # 链表逆转，有头节点可以原地逆转
    def reverse(self):
        tail = self.head.next
        cur = tail.next
        while cur:
            tail.next = cur.next
            cur.next = self.head.next
            self.head.next = cur
            cur = tail.next

    # 链表判空
    def isEmpty(self):
        if self.head.next == None:
            return True
        else:
            return False

    # 链表长度
    def length(self):
        if self.isEmpty():
            return 0
        
        len = 0
        p = self.head.next
        while p:
            len += 1
            p = p.next
        return len


if __name__ == '__main__':
    l = LinkedList()
    l.creatList(5)
    l.traveList()
    l.insert(5, 100)
    l.traveList()
    l.remove(5)
    l.traveList()

二：不带头节点

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


def creat_List(l, n):
    l.data = int(input())
    p = l
    for i in range(n-1):
        node = ListNode()
        node.data = int(input())
        p.next = node
        p = p.next
    
    p.next = None
    
def length(l):
    p = l
    len = 0
    while p:
        len += 1
        p = p.next
    return len

# 链表逆转
def reverse(l):
    res = pre = None
    p = l
    while p:
        pre = p.next
        p.next = res
        res = p
        p = pre
    return res 

def traverse(l):
    p = l
    while p:
        print(p.data, ' ', end='')
        p = p.next
    
    print()

if __name__ == '__main__':
    l = ListNode()
    creat_List(l, 5)
    traverse(l)
    ll = reverse(l)
    traverse(ll)
    traverse(l)