链表——增删查改

题目

题目解析

　　一个很基础的关于链表的增删查改题目，学过数据结构的应该都蛮熟的吧（^^），为了更好的完成题目，我们可以将其变为一个菜单，直接使用。

代码

增

bool Push(ListNode** head, int num)
{
    ListNode* new_node = new ListNode{ num, NULL }; 
    if (!new_node)  
    {
        return false;
    }
    if (*head == NULL)
    {
        *head = new_node;
    }
    else
    {
        ListNode* current = *head;
        while (current->next_node)
        {
            current = current->next_node;
        }
        current->next_node = new_node;
    }
    return true;
}

删

bool Pop(ListNode** head, int num)
{
    bool found = false;
    ListNode dummy{ num,NULL }; // 创建一个dummy节点，其值设置为0  
    dummy.next_node = *head;
    ListNode* current = &dummy;
 
    while (current->next_node != NULL)
    {
        if (current->next_node->num == num)
        {
            ListNode* temp = current->next_node;
            current->next_node = current->next_node->next_node;
            delete temp;
            found = true;
            break; // 找到后退出循环  
        }
        current = current->next_node;
    }
 
    *head = dummy.next_node; // 更新头节点  
    return found;
}

查

ListNode* Find(ListNode *head, int num)
{
    ListNode* current = head;
    while (current)
    {
        if (current->num == num) 
        {
            return current;
        }
        current = current->next_node;
    }
    return NULL;
}

改

bool Updata(ListNode** head, int num1, int num2)
{
    ListNode* current = *head;
    while (current)
    {
        if (current->num == num1) 
        {
            current->num = num2;
            return true;
        }
        current = current->next_node;
    }
    return false;
}

总代码

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/*2024-3-15 rou*/
#include<iostream>
#include<string>
using namespace std;
 
struct ListNode
{
    int num;
    struct ListNode *next_node;
};
 
//增
bool Push(ListNode** head, int num)
{
    ListNode* new_node = new ListNode{ num, NULL };
    if (!new_node)
    {
        return false;
    }
    if (*head == NULL)
    {
        *head = new_node;
    }
    else
    {
        ListNode* current = *head;
        while (current->next_node)
        {
            current = current->next_node;
        }
        current->next_node = new_node;
    }
    return true;
}
 
//删
bool Pop(ListNode** head, int num)
{
    bool found = false;
    ListNode dummy{ num,NULL }; // 创建一个dummy节点，其值设置为0  
    dummy.next_node = *head;
    ListNode* current = &dummy;
 
    while (current->next_node != NULL)
    {
        if (current->next_node->num == num)
        {
            ListNode* temp = current->next_node;
            current->next_node = current->next_node->next_node;
            delete temp;
            found = true;
            break; // 找到后退出循环  
        }
        current = current->next_node;
    }
 
    *head = dummy.next_node; // 更新头节点  
    return found;
}
 
//查
ListNode* Find(ListNode *head, int num)
{
    ListNode* current = head;
    while (current)
    {
        if (current->num == num) 
        {
            return current;
        }
        current = current->next_node;
    }
    return NULL;
}
 
//改
bool Updata(ListNode** head, int num1, int num2)
{
    ListNode* current = *head;
    while (current)
    {
        if (current->num == num1) 
        {
            current->num = num2;
            return true;
        }
        current = current->next_node;
    }
    return false;
}
 
//打印链表
bool PrintList(ListNode** head)
{
    cout << "是否需要打印链表？（1.是 ，2.不是）" << endl;
 
    int yes_or_no;
    cin >> yes_or_no;
 
    if (yes_or_no == 1)
    {
        ListNode* current = *head;
        while (current)
        {
            cout << current->num << " ";
            current=current->next_node;
        }
        cout << endl;
        return true;
    }
    else if (yes_or_no == 2)
    {
        return false;
    }
    else
    {
        cout << "输入错误，取消打印" << endl;
        return false;
    }
}
 
bool Clear(ListNode** head)
{
    ListNode* temp;
    while (*head)
    {
        temp = *head;
        *head = (*head)->next_node;
        delete temp;
    }
    return true;
}
 
int main()
{
    ListNode* head = NULL;
    bool keepRunning = true;
 
    cout << "请输入要插入的数据数量(数量在100以内):" << endl;
 
    int count;
    cin >> count;
 
    if (count > 100 || count < 0)
    {
        cout << "输入的数据数量不在有效范围内，请重新输入：" << endl;
        return 1;
    }
 
    for (int i = 0; i < count; ++i) 
    {
        int num;
        cout << "请输入第 " << i + 1 << " 个数据:" << endl;
        cin >> num;
        if (!Push(&head, num)) {
            cout << "内存分配失败，无法插入数据。" << endl;
            Clear(&head);
            return 1;
        }
    }
     
    PrintList(&head);
 
    while (keepRunning)
    {
         
        int choice;
     
        do {
            cout << "请选择要执行的操作：" << endl;
            cout << "1.增加数据" << endl;
            cout << "2.删除数据" << endl;
            cout << "3.查询数据" << endl;
            cout << "4.修改数据" << endl;
            cout << "5.退出程序" << endl;
 
            cin >> choice;
 
            switch (choice)
            {
                case 1:
                {
                    cout << "请输入要增加的数据数量：" << endl;
                    int addCount;
                    cin >> addCount;
 
                    for (int i = 0; i < addCount; ++i)
                    {
                        int num;
                        cout << "请输入要添加的数据：" << endl;
                        cin >> num;
                        if (!Push(&head, num))
                        {
                            cout << "内存分配失败，无法插入数据" << endl;
                            break;
                        }
                    }
                    break;
                }
 
                case 2:
                {
                    cout << "请输入要删除的数据：" << endl;
                    int num;
                    cin >> num;
 
                    if (Pop(&head, num))
                    {
                        cout << "删除数据" << num << "成功" << endl;
                    }
                    else
                    {
                        cout << "删除数据" << num << "失败" << endl;
                    }
                    break;
                }
 
                case 3:
                {
                    cout << "请输入要查询的数据：" << endl;
                    int num;
                    cin >> num;
                    ListNode* found = Find(head, num);
                    if (found)
                    {
                        cout << "找到数据 " << num << endl;
                    }
                    else
                    {
                        cout << "未找到数据 " << num << endl;
                    }
                    break;
                }
 
                case 4:
                {
                    cout << "请输入要将数据num1修改为数据num2的数值：" << endl;
                    int num1, num2;
                    cout << "num1:";
                    cin >> num1;
                    cout << endl << "num2：";
                    cin >> num2;
                    if (Updata(&head, num1, num2))
                    {
                        cout << "数据 " << num1 << " 修改为 " << num2 << " 成功" << endl;
                    }
                    else
                    {
                        cout << "数据 " << num1 << " 未找到，修改失败" << endl;
                    }
                    break;
                }
 
                case 5:
                    cout << "退出程序。" << endl;
                    keepRunning = false;
                    break;
 
                default:
                    cout << "无效的选择，请重新选择" << endl;
                    break;
            }
 
            // 打印链表  
            PrintList(&head);
 
        } while (choice != 5);
    }
 
    // 清除链表  
    Clear(&head);
 
    return 0;
}