数据结构与算法之单链表和单向循环链表的实现及区别

IOS

2024-01-26 05:22:20

单链表与单向循环链表的基本概念

1. 单链表

单链表是一种线性表，它由一系列的节点组成，每个节点包含一个数据项和一个指向下一个节点的指针。单链表的第一个节点称为头节点，最后一个节点称为尾节点。

2. 单向循环链表

单向循环链表是单链表的变种，它的尾节点指向头节点，形成一个闭合的环。单向循环链表的优势在于，它可以方便地进行遍历，并且不需要显式地记录尾节点的位置。

单链表与单向循环链表的实现

1. 单链表的实现

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

class SingleLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def insert_at_head(self, data):
        new_node = Node(data)
        new_node.next = self.head
        self.head = new_node
        if self.tail is None:
            self.tail = new_node

    def insert_at_tail(self, data):
        new_node = Node(data)
        if self.tail is None:
            self.head = new_node
            self.tail = new_node
        else:
            self.tail.next = new_node
            self.tail = new_node

    def delete_at_head(self):
        if self.head is None:
            return
        self.head = self.head.next
        if self.head is None:
            self.tail = None

    def delete_at_tail(self):
        if self.tail is None:
            return
        current_node = self.head
        while current_node.next != self.tail:
            current_node = current_node.next
        current_node.next = None
        self.tail = current_node

    def find(self, data):
        current_node = self.head
        while current_node is not None:
            if current_node.data == data:
                return current_node
            current_node = current_node.next
        return None

    def traverse(self):
        current_node = self.head
        while current_node is not None:
            print(current_node.data)
            current_node = current_node.next

### 2. 单向循环链表的实现

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

class SingleCircularLinkedList:
    def __init__(self):
        self.head = None

    def insert_at_head(self, data):
        new_node = Node(data)
        if self.head is None:
            new_node.next = new_node
            self.head = new_node
        else:
            current_node = self.head
            while current_node.next != self.head:
                current_node = current_node.next
            current_node.next = new_node
            new_node.next = self.head

    def insert_at_tail(self, data):
        new_node = Node(data)
        if self.head is None:
            new_node.next = new_node
            self.head = new_node
        else:
            current_node = self.head
            while current_node.next != self.head:
                current_node = current_node.next
            current_node.next = new_node
            new_node.next = self.head

    def delete_at_head(self):
        if self.head is None:
            return
        if self.head.next == self.head:
            self.head = None
        else:
            current_node = self.head
            while current_node.next != self.head:
                current_node = current_node.next
            current_node.next = self.head.next
            self.head = self.head.next

    def delete_at_tail(self):
        if self.head is None:
            return
        if self.head.next == self.head:
            self.head = None
        else:
            current_node = self.head
            while current_node.next.next != self.head:
                current_node = current_node.next
            current_node.next = self.head

    def find(self, data):
        current_node = self.head
        while current_node.next != self.head:
            if current_node.data == data:
                return current_node
            current_node = current_node.next
        if current_node.data == data:
            return current_node
        return None

    def traverse(self):
        current_node = self.head
        while current_node.next != self.head:
            print(current_node.data)
            current_node = current_node.next
        print(current_node.data)