链表的构建及基础操作

How to create a Linked List in Python

• A linked list is a data structure made of a chain of node objects. Each node contains a value and a pointer to the next node in the chain.
• The head pointer points to the first node, and the last element of the list points to null. When the list is empty, the head pointer points to null.

# 节点类
class Node(object):
    def __init__(self, data, Next = None):
        self.data = data
        self.next = Next

# 链表类：用于存放节点
class LinkedList(object):
    def __init__(self):
        self.head = None

    # 判断链表是否为空
    def isEmpty(self):
        return self.head == None

    # 给链表添加节点
    def add(self, data):
        newNode=Node(data) # 构建一个新的节点，该节点的值为data
        # 头结点存在，把cur指向头结点，cur逐步跳到链表尾部，然后添加节点
        if (self.head):
            cur=self.head
            while (cur.next):
                cur = cur.next
            cur.next=newNode # 通过next，在尾部不断连接节点
        else: # 这是一个空链表，则在头结点处添加该节点
            self.head=newNode

    # 判断链表的长度
    def size(self):
        count=0
        cur=self.head
        while(cur):
            count+=1
            cur=cur.next
        print(count)

    # 搜索某个元素是否存在
    def search(self,item):
        cur=self.head
        while(cur):
            if cur.data==item:
                return True
            else:
                cur=cur.next
        return False


    # 打印该链表
    def printLL(self):
        cur=self.head
        while(cur):
            print(cur.data)
            cur=cur.next

if __name__ == '__main__':
    L=LinkedList()
    L.add(1)
    L.add(2)
    L.add(3)
    # L.size()  
    # print(L.search(2)==True)
    L.printLL()

#include <iostream>

struct ListNode {
    int val;
    ListNode *next;
    ListNode() : val(0), next(nullptr) {}
    ListNode(int x) : val(x), next(nullptr) {}
    ListNode(int x, ListNode *next) : val(x), next(next) {}
};

class LinkedList {
private:
    ListNode *head;
public:
    LinkedList():head(nullptr){} // 构造函数构建一个空的链表

    //    判断链表是否为空
    bool isEmpty() const {
        return head == nullptr;
    }

//    添加节点
    void add(int data) {
//        创建一个新节点
        ListNode *newNode = new ListNode(data);
        if (head) {
            ListNode *cur = head;
            while (cur->next) {
                cur = cur->next;
            }
            cur->next = newNode;
        } else
            head = newNode;
    }

//    判断链表的长度
    int size() {
        int count = 0;
        ListNode *cur = head;
        while (cur) {
            count++;
            cur = cur->next;
        }
        return count;
    }

//     搜索某个元素是否存在
    bool search(int data) {
        ListNode *cur = head;
        while (cur) {
            if (cur->val == data) {
                return true;
            }
            else
                cur = cur->next;
        }
        return false;
    }

//    打印该链表
    void printLL() {
        ListNode *cur = head;
        while (cur) {
            std::cout << cur->val << std::endl;
            cur = cur->next;
        }
    }


};

int main(){
    ListNode n(1);
    LinkedList L;
    L.add(1);
    L.add(2);
    L.add(3);
//    std::cout<<L.size()<<std::endl;
//    std::cout<<L.search(2)<<std::endl;
    L.printLL();
}