链表
- 介绍
- 单向链表
- 节点结构
- 创建节点
- 插入节点
- 删除节点
- 遍历链表
- 尾部插入
- 查找节点
- 链表反转
- 示例程序
- 程序1
- 程序2
介绍
链表是一种常见的数据结构,用于存储一系列线性数据。与数组不同,链表中的元素在内存中不必是连续存放的,而是通过指针将每个元素(节点)链接在一起。链表有很多种类型,例如单向链表、双向链表和循环链表。这里我们主要介绍单向链表。
单向链表
单向链表由一系列节点组成,每个节点包含两个部分:
- 数据部分:存储节点的实际内容。
- 指针部分:存储指向下一个节点的指针。
节点结构
在 C 语言中,我们可以通过定义一个结构体来表示链表的节点:
struct Node {int data; // 数据部分struct Node* next; // 指针部分
};
创建节点
可以通过动态内存分配函数 malloc
来创建新节点:
#include <stdio.h>
#include <stdlib.h>// 定义节点结构
struct Node {int data;struct Node* next;
};// 创建新节点
struct Node* createNode(int data) {struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));if (!newNode) {printf("内存分配失败\n");exit(1);}newNode->data = data;newNode->next = NULL;return newNode;
}
插入节点
我们可以在链表的头部或尾部插入节点。以头部插入为例:
// 头部插入
void insertAtHead(struct Node** head, int data) {struct Node* newNode = createNode(data);newNode->next = *head;*head = newNode;
}
删除节点
删除链表中的节点也很常见。假设我们要删除值为 key
的节点:
void deleteNode(struct Node** head, int key) {struct Node* temp = *head;struct Node* prev = NULL;// 如果头节点本身就是要删除的节点if (temp != NULL && temp->data == key) {*head = temp->next;free(temp); // 释放内存return;}// 搜索要删除的节点while (temp != NULL && temp->data != key) {prev = temp;temp = temp->next;}// 如果没找到要删除的节点if (temp == NULL) return;// 断开链接并释放内存prev->next = temp->next;free(temp);
}
遍历链表
遍历链表可以通过循环来实现:
void printList(struct Node* head) {struct Node* current = head;while (current != NULL) {printf("%d -> ", current->data);current = current->next;}printf("NULL\n");
}
尾部插入
尾部插入与头部插入类似,我们需要找到链表的最后一个节点,然后将新节点添加到末尾。
// 尾部插入
void insertAtTail(struct Node** head, int data) {struct Node* newNode = createNode(data);if (*head == NULL) {*head = newNode;return;}struct Node* temp = *head;while (temp->next != NULL) {temp = temp->next;}temp->next = newNode;
}
查找节点
查找链表中的某个节点,返回其位置或者指针:
struct Node* searchNode(struct Node* head, int key) {struct Node* current = head;while (current != NULL) {if (current->data == key) {return current;}current = current->next;}return NULL; // 未找到
}
链表反转
反转链表是一个经典的问题,可以通过迭代的方式实现:
void reverseList(struct Node** head) {struct Node* prev = NULL;struct Node* current = *head;struct Node* next = NULL;while (current != NULL) {next = current->next; // 暂存下一个节点current->next = prev; // 反转当前节点的指针prev = current; // 移动 prev 指针current = next; // 移动 current 指针}*head = prev;
}
示例程序
程序1
#include <stdio.h>
#include <stdlib.h>struct Node {int data;struct Node* next;
};struct Node* createNode(int data) {struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));if (!newNode) {printf("内存分配失败\n");exit(1);}newNode->data = data;newNode->next = NULL;return newNode;
}void insertAtHead(struct Node** head, int data) {struct Node* newNode = createNode(data);newNode->next = *head;*head = newNode;
}void deleteNode(struct Node** head, int key) {struct Node* temp = *head;struct Node* prev = NULL;if (temp != NULL && temp->data == key) {*head = temp->next;free(temp);return;}while (temp != NULL && temp->data != key) {prev = temp;temp = temp->next;}if (temp == NULL) return;prev->next = temp->next;free(temp);
}void printList(struct Node* head) {struct Node* current = head;while (current != NULL) {printf("%d -> ", current->data);current = current->next;}printf("NULL\n");
}int main() {struct Node* head = NULL;insertAtHead(&head, 1);insertAtHead(&head, 2);insertAtHead(&head, 3);printf("Created Linked List: ");printList(head);deleteNode(&head, 2);printf("Linked List after deletion of 2: ");printList(head);return 0;
}
输出结果:
程序2
#include <stdio.h>
#include <stdlib.h>// 定义节点结构
struct Node {int data;struct Node* next;
};// 创建新节点
struct Node* createNode(int data) {struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));if (!newNode) {printf("内存分配失败\n");exit(1);}newNode->data = data;newNode->next = NULL;return newNode;
}// 头部插入
void insertAtHead(struct Node** head, int data) {struct Node* newNode = createNode(data);newNode->next = *head;*head = newNode;
}// 尾部插入
void insertAtTail(struct Node** head, int data) {struct Node* newNode = createNode(data);if (*head == NULL) {*head = newNode;return;}struct Node* temp = *head;while (temp->next != NULL) {temp = temp->next;}temp->next = newNode;
}// 删除节点
void deleteNode(struct Node** head, int key) {struct Node* temp = *head;struct Node* prev = NULL;if (temp != NULL && temp->data == key) {*head = temp->next;free(temp);return;}while (temp != NULL && temp->data != key) {prev = temp;temp = temp->next;}if (temp == NULL) return;prev->next = temp->next;free(temp);
}// 查找节点
struct Node* searchNode(struct Node* head, int key) {struct Node* current = head;while (current != NULL) {if (current->data == key) {return current;}current = current->next;}return NULL;
}// 反转链表
void reverseList(struct Node** head) {struct Node* prev = NULL;struct Node* current = *head;struct Node* next = NULL;while (current != NULL) {next = current->next;current->next = prev;prev = current;current = next;}*head = prev;
}// 打印链表
void printList(struct Node* head) {struct Node* current = head;while (current != NULL) {printf("%d -> ", current->data);current = current->next;}printf("NULL\n");
}int main() {struct Node* head = NULL;insertAtHead(&head, 1);insertAtHead(&head, 2);insertAtHead(&head, 3);printf("初始链表: ");printList(head);// 测试尾部插入insertAtTail(&head, 4);printf("尾部插入 4 后的链表: ");printList(head);// 测试删除节点deleteNode(&head, 2);printf("删除节点 2 后的链表: ");printList(head);// 测试查找节点struct Node* foundNode = searchNode(head, 3);if (foundNode) {printf("找到节点 3\n");} else {printf("未找到节点 3\n");}// 测试反转链表reverseList(&head);printf("反转后的链表: ");printList(head);return 0;
}
输出结果: