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

/*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;
}