单链表操作

1、单链表结构

typedef struct ListNode {int data;ListNode *next;} ListNode;

2、单链表创建

//创建一个单链表 ListNode *create_list() {int len = 0;ListNode *head, *p, *q;int data;head = (ListNode*)malloc(sizeof(ListNode));q = head;while(1) {cout << "Please input the data: " ;cin >> data;if(data == 0) break;p = (ListNode*)malloc(sizeof(ListNode));p->data = data;q->next = p;q = p;}q->next = NULL;return head;}

3、单链表打印

//单链表的打印 void print_list(ListNode *head) {ListNode *p = head->next;if(p == NULL) {cout << "List is empty." << endl;return;}while(p != NULL) {cout << p->data;p = p->next;if(p != NULL) cout << " -> ";}cout << endl;}

4、单链表长度

//测试单链表的长度int length_list(ListNode *head) {ListNode *p = head->next;int len = 0;while(p != NULL) {len++;p = p->next;}return len;} 

5、单链表查找

//单链表的查找ListNode *search_list(ListNode *head, int pos) {ListNode *p = head->next;if(pos < 0) {cout << "Incorrect postion to search list." << endl;return NULL;}if(pos == 0) {return head;}if(p == NULL) {cout << "List is empty." << endl;return NULL;}while(--pos) {if((p = p->next) == NULL) {cout << "Incorrenct postion to search list." << endl;return NULL;}}return p;} 

6、单链表插入

//单链表的插入ListNode *insert_list(ListNode *head, int pos, int data) {ListNode *p, *item;item = (ListNode*)malloc(sizeof(ListNode));item->data = data;if(pos == 0) {item->next = head->next;head->next = item;return head;}p = search_list(head, pos);if(p != NULL) {item->next = p->next;p->next = item;}return head;} 

7、单链表删除

//单链表的删除ListNode *delete_list(ListNode *head, int pos) {ListNode *p = head->next;ListNode *item = NULL;if(p == NULL) {cout << "List is empty." << endl;return NULL;}p = search_list(head, pos - 1);if(p != NULL && p->next != NULL) {item = p->next;p->next = item->next;free(item);}return head;} 

8、单链表逆置

//将单链表逆置//例如原链表为: 1->2->3->4；逆置后为: 4->3->2->1 ListNode *reverse_list(ListNode *head) {ListNode *p, *q;if(head->next == NULL) {return head;}p = head->next;q = p->next;p->next = NULL;while(q != NULL) {ListNode *r = q->next;q->next = head->next;head->next = q;q = r;}return head;} 

9、单链表查找中间值

//查找单链表中间的元素，只需要一次遍历ListNode *search_middle(ListNode *head) {ListNode *current = NULL;ListNode *middle = NULL;int i = 0, j = 0;current = middle = head->next;while(current != NULL) {if(j < i / 2) {j++;middle = middle->next;}i++;current = current->next;}return middle;} 

10、单链表测试

int main(){int pos, data;ListNode *head, *item;head = create_list();cout << endl;print_list(head);cout << endl;int len = length_list(head);cout << "The length is : " << len << endl;cout << endl;cout << "Please input search pos: ";cin >> pos;item = search_list(head, pos);if(item != NULL) {cout << "The pos " << pos << "'th data is: " << item->data << endl;}cout << endl;cout << "The input insert pos and data is: ";cin >> pos >> data;head = insert_list(head, pos, data);print_list(head);cout << endl;cout << "Please input the delete pos: ";cin >> pos;head = delete_list(head, pos);print_list(head);head = reverse_list(head);print_list(head);item = search_middle(head);cout << "The middle data is : " << item->data << endl;}