剑指offer之C语言实现链表（两种方式）
【摘要】 1 问题
用C语言实现链表
2 代码实现
#include <stdio.h>#include <stdlib.h> #define true 0#define false -1 typedef struct Node{ int value; struct Node *next;} List; /*...
1 问题
用C语言实现链表
2 代码实现
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#include <stdio.h>
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#include <stdlib.h>
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#define true 0
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#define false -1
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typedef struct Node
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{
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int value;
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struct Node *next;
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} List;
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/**
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*初始化链表
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*/
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struct Node* init_list()
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{
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struct Node *head = (struct Node*)malloc(sizeof(struct Node));
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if (head)
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{
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head->next = NULL;
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return head;
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}
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return NULL;
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}
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/*
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*创建节点
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*/
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struct Node* create_node(int value)
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{
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struct Node *node = (struct Node*)malloc(sizeof(struct Node));
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if (node)
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{
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node->value = value;
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return node;
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}
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return NULL;
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}
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/*
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*第一种方法插入节点
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*/
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int insert_list(struct Node **head, List* node)
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{
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if (*head == NULL || node == NULL)
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{
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printf("head or node is NULL");
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return false;
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}
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node->next = *head;
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*head = node;
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return true;
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}
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/*
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*第二种方法插入节点
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*/
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int insert_list1(struct Node *head, List* node)
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{
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if (head == NULL || node == NULL)
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{
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printf("head or node is NULL");
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return false;
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}
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node->next = head->next;
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head->next = node;
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return true;
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}
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/*
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*第一种方法打印
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*/
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void print_list(List *head)
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{
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if (head == NULL)
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{
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printf("head is NULL\n");
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return;
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}
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while (head->next != NULL)
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{
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printf("value is %d\n", head->value);
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head = head->next;
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}
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}
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/*
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*第二种方法打印
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*/
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void print_list1(List *head)
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{
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if (head == NULL)
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{
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printf("head is NULL\n");
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return;
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}
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struct Node *p = head->next;
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while (p != NULL)
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{
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printf("value is %d\n", p->value);
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p = p->next;
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}
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-
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}
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/*
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*更具这个值能否能到节点
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*/
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struct Node* get_node(List *head, int value)
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{
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if (head == NULL)
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return NULL;
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struct Node *p = head;
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while (p != NULL)
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{
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if (p->value == value)
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{
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return p;
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}
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p = p->next;
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}
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return NULL;
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}
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/*
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*第一种方法删除节点
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*/
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int delete_node(struct Node **head, struct Node *node)
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{
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if (*head == NULL)
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return false;
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if ((*head) == node)
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{
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*head = (*head)->next;
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return true;
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}
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struct Node *p = *head;
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while ((*head)->next != NULL)
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{
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if ((*head)->next == node)
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{
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(*head)->next =(*head)->next->next;
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*head = p;
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return true;
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}
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*head = (*head)->next;
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}
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*head = p;
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return false;
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}
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/*
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*第二种方法删除节点
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*/
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int delete_node1(struct Node *head, struct Node *node)
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{
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if (head == NULL)
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return false;
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while (head->next != NULL)
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{
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if (head->next == node)
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{
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head->next = head->next->next;
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return true;
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}
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head = head->next;
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}
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return false;
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}
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/*
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*释放链表
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*/
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int free_list(List *head)
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{
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if (head == NULL)
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return false;
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struct Node *p = NULL;
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while(head != NULL)
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{
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p = head;
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head = head->next;
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free(p);
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}
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return true;
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}
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int main()
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{
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struct Node* head = NULL;
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struct Node* node1 = NULL, *node2 = NULL, *node3 = NULL;
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struct Node* node4 = NULL, *node5 = NULL, *node6 = NULL;
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head = init_list();
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if (!head)
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{
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printf("init head fail\n");
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}
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node1 = create_node(5);
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node2 = create_node(4);
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node3 = create_node(3);
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node4 = create_node(2);
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node5 = create_node(1);
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node6 = create_node(3);
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insert_list1(head, node1);
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insert_list1(head, node2);
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insert_list1(head, node3);
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insert_list1(head, node4);
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insert_list1(head, node5);
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insert_list1(head, node6);
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print_list1(head);
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printf("first print_list---------------\n");
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delete_node1(head, node1);
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print_list1(head);
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printf("second print_list--------------\n");
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free_list(head);
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head = NULL;
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head = init_list();
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if (!head)
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{
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printf("init head fail\n");
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}
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node1 = create_node(5);
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node2 = create_node(4);
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node3 = create_node(3);
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node4 = create_node(2);
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node5 = create_node(1);
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node6 = create_node(3);
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insert_list(&head, node1);
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insert_list(&head, node2);
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insert_list(&head, node3);
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insert_list(&head, node4);
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insert_list(&head, node5);
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insert_list(&head, node6);
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print_list(head);
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printf("third print_list---------------\n");
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delete_node(&head, node4);
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print_list(head);
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printf("four print_list---------------\n");
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struct Node *result = get_node(head, 4);
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if (result)
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{
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printf("list contain node and the value of node is %d\n", result->value);
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}
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else
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{
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printf("list do not contain the node\n");
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}
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free_list(head);
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head = NULL;
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return 0;
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}
3 运行结果
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value is 3
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value is 1
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value is 2
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value is 3
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value is 4
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value is 5
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first print_list---------------
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value is 3
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value is 1
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value is 2
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value is 3
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value is 4
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second print_list--------------
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value is 3
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value is 1
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value is 2
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value is 3
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value is 4
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value is 5
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third print_list---------------
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value is 3
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value is 1
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value is 3
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value is 4
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value is 5
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four print_list---------------
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list contain node and the value of node is 4
4 总结
很明显第二种方式更换简单好理解，在函数里面如果我们传递指针进去，然后想修改这个指针的话，我们直接给这个指针赋值来改变这个指针是不可以的，因为是停时变量，我们直接可以返回新malloc的指针或者函数传递二级指针作为参数，在函数里面修改这个指针，同时我们把头结点传递函数里面去，我们直接操作head->next = head->next->next;这些都会有效.
用C语言实现的话，我们喜欢搞个头结点，然后每个函数里面传入头结点，我们函数里面改变的是head->next的值，但是我们就算移动了head节点，比如head = head->next; 但是实际上没有影响，因为是零时变量，最后的head的位置还是没有动
文章来源: chenyu.blog.csdn.net，作者：chen.yu，版权归原作者所有，如需转载，请联系作者。
原文链接：chenyu.blog.csdn.net/article/details/86515602
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