笔试面试常考数据结构-单链表常用操作编程实现

单链表是笔试以及面试手写代码中常考的数据结构之一。下面实现了单链表的常见操作：创建单链表、删除节点、打印单链表（包括正向打印以及逆向打印）、反转单链表、找出单链表的倒数第K个节点、合并两个有序单链表等操作。

代码（C++）：

//笔试面试单链表常用操作编程实现#include <iostream>#include <stack>#include <cstdlib>using namespace std;//单链表节点数据结构定义typedef struct link_node_s{    int m_val;    struct link_node_s *next;}link_node_t,*link_list_t;//函数:创建单链表(头插法)link_list_t create_linklist(int *a,int n);//函数:打印单链表(从头到尾)void print_linklist(link_list_t head);//函数:打印单链表(从尾到头)void print_linklist_reverse(link_list_t head);//函数:新建链表节点link_list_t creart_linknode(int val);//函数:删除链表中的某一个节点(前提条件:该节点一定存在)//性能要求:在O(1)时间复杂度内实现void delete_node_exist(link_list_t *head,link_list_t node_deleted);//函数:删除链表中数据值等于给定值的节点void delete_node(link_list_t *head,int val);//函数:获得链表中的倒数第K个节点link_list_t get_kth_node(link_list_t head,int k);//函数:反转链表link_list_t reverse_linklist(link_list_t head);//函数:合并两个已排序的链表(递归方法实现)link_list_t merge_linklist_recursive(link_list_t head1,link_list_t head2);int main(){    const int num1 = 8;    const int num2 = 10;    int *a = new int[num1];    int *b = new int[num2];    int *a_sorted = new int[num1];    int *b_sorted = new int[num2];    srand(1);    for(int i = 0;i < num1;++i){        *(a + i) = rand() % 100;        *(a_sorted + i) = 50 - i * 2 + 8;    }    for(int i = 0;i < num2;++i){        *(b + i) = rand() % 200;        *(b_sorted + i) = 50 - i * 4 + 1;    }    cout << "**********创建链表测试**********" << endl;    link_list_t list1 = create_linklist(a,num1);    link_list_t list2 = create_linklist(b,num2);    link_list_t list_sorted1 = create_linklist(a_sorted,num1);    link_list_t list_sorted2 = create_linklist(b_sorted,num2);    cout << "**********输出链表测试(正向输出)**********" << endl;    cout << "链表1:" << endl;    print_linklist(list1);    cout << "链表1(已序):" << endl;    print_linklist(list_sorted1);    cout << "链表2(已序):" << endl;    print_linklist(list_sorted2);    cout << "**********输出链表测试(逆向输出)**********" << endl;    print_linklist_reverse(list1);    cout << "**********获取链表的倒数第K个节点测试**********" << endl;    int k = 3;    link_list_t kth_node = get_kth_node(list1,k);    if(NULL == kth_node)        cout << "链表中倒数第" << k << "个节点不存在" << endl;    else        cout << "链表中倒数第" << k <<"个节点是: " <<kth_node->m_val << endl;     k = 8;    kth_node = get_kth_node(list1,k);    if(NULL == kth_node)        cout << "链表中倒数第" << k << "个节点不存在" << endl;    else        cout << "链表中倒数第" << k <<"个节点是: " <<kth_node->m_val << endl;     k = 11;    kth_node = get_kth_node(list1,k);    if(NULL == kth_node)        cout << "链表中倒数第" << k << "个节点不存在" << endl;    else        cout << "链表中倒数第" << k <<"个节点是: " <<kth_node->m_val << endl;     cout << "**********删除链表中一定存在的节点测试(输入参数是要删除的节点指针)**********" << endl;    link_list_t node_deleted = list1;    while(node_deleted->m_val != *(a + 4))        node_deleted = node_deleted->next;    cout << "删除节点" << *(a + 4) << "之后的单链表:" << endl;    delete_node_exist(&list1,node_deleted);    print_linklist(list1);    node_deleted = list1;    while(node_deleted->m_val != *(a + 6))        node_deleted = node_deleted->next;    cout << "删除节点" << *(a + 6) << "之后的单链表:" << endl;    delete_node_exist(&list1,node_deleted);    print_linklist(list1);    cout << "**********删除链表中值等于给定值的节点测试(不一定存在,输入参数是int型值)**********" << endl;    const int val_deleted = 22;    delete_node(&list1,val_deleted);    cout << "删除值等于" << val_deleted << "之后的链表:" << endl;    print_linklist(list1);    cout << "**********合并链表测试**********" << endl;    link_list_t merge_list_head = merge_linklist_recursive(list_sorted1,list_sorted2);    print_linklist(merge_list_head);    cout << "**********逆转链表测试**********" << endl;    link_list_t head_reverse = reverse_linklist(merge_list_head);    cout << "逆转之后的链表:" << endl;    cout << "头节点:" << head_reverse->m_val << endl;    print_linklist(head_reverse);    return 0;}//函数:创建单链表(头插法)link_list_t create_linklist(int *a,int n){    link_list_t head = NULL;    if(NULL == a || 0 == n)        return NULL;    for(int i = 0;i < n;++i){        link_list_t new_node = creart_linknode(*(a + i));        if(NULL == head){            head = new_node;        }        else{            new_node->next = head;            head = new_node;        }    }    return head;}//函数:新建链表节点link_list_t creart_linknode(int val){    link_list_t node = new link_node_t;    node->m_val = val;    node->next = NULL;    return node;}//函数:打印单链表void print_linklist(link_list_t head){    link_list_t node = head;    cout << "正向输出单链表" << endl;    while(node != NULL){        cout << node->m_val << " ";        node = node->next;    }    cout << endl;    return;}//函数:打印单链表(从尾到头)void print_linklist_reverse(link_list_t head){    stack<int> node_stack;    link_list_t node = head;    while(node != NULL){        node_stack.push(node->m_val);        node = node->next;    }    cout << "逆向输出单链表" << endl;    while(!node_stack.empty()){        cout << node_stack.top() << " ";        node_stack.pop();    }    cout << endl;    return;}//函数:删除链表中的某一个节点(前提条件:该节点一定存在)//性能要求:在O(1)时间复杂度内实现void delete_node_exist(link_list_t *head,link_list_t node_deleted){    //算法思想:    //通过拷贝要删除节点的后继节点的内容覆盖要删除节点的内容,然后删除要删除节点的后继节点即可    //要考虑的特殊情况是:要删除的节点是链表尾部节点,仍然需要遍历链表    if(NULL == head || NULL == node_deleted)        return;    //要删除的节点不是尾节点    if(node_deleted->next != NULL){        link_list_t next_node = node_deleted->next;        node_deleted->m_val = next_node->m_val;        node_deleted->next = next_node->next;        delete next_node;        next_node = NULL;    }    //链表中只有一个节点    else if(*head == node_deleted){        delete node_deleted;        node_deleted = NULL;        *head = NULL;    }    //要删除的节点是尾节点    else{        link_list_t node = *head;        while(node->next != node_deleted)            node = node->next;        node->next = node_deleted->next;        delete node_deleted;        node_deleted = NULL;    }    return;}//函数:获得链表中的倒数第K个节点link_list_t get_kth_node(link_list_t head,int k){    //性能:只需遍历链表一遍即可    //算法思想:设置两个指针,一个指向链表头部,一个指向第k个节点,然后两个指针同时向后移动,当第二个指针指向链表的尾节点时,第一个指针指向的节点便是倒数第K个节点    //注意代码的鲁棒性,防止程序的崩溃    if(NULL == head || k <= 0)        return NULL;    //设置两个指针    link_list_t p1 = head,p2 = head;    int i = 0;    //第二个指针向前走k-1步    while(i < k - 1 && p2->next != NULL){        p2 = p2->next;        ++i;    }    //注意链表中总节点数小于K的情况    if(i != k - 1 && NULL == p2->next)        return NULL;    //两个指针同时向后前进    while(p2->next != NULL){        p1 = p1->next;        p2 = p2->next;    }    return p1;}//函数:反转链表//返回值:反转之后的链表头节点link_list_t reverse_linklist(link_list_t head){    //链表为空或者只有一个节点    if(NULL == head || NULL == head->next)        return head;    link_list_t prev_node = NULL,next_node,cur_node = head,head_reverse;    while(cur_node != NULL){        next_node = cur_node->next;        if(NULL == next_node)            head_reverse = cur_node;//原链表尾节点即逆转后链表的头节点        cur_node->next = prev_node;        prev_node = cur_node;        cur_node = next_node;    }    return head_reverse;}//函数:删除链表中数据值等于给定值的节点void delete_node(link_list_t *head,int val){    if(NULL == head){        cout << "Delete node failed :The node to be delete not exist!" << endl;        return;    }    if(val == (*head)->m_val){        link_list_t node = *head;        *head = (*head)->next;        delete node;        return;    }    //首先判断该节点是否存在链表中    link_list_t node = *head;    while(node->next != NULL){        if(val == node->next->m_val)            break;        node = node->next;    }    //存在满足条件的节点    if(node->next != NULL){        link_list_t node_delete = node->next;        node->next = node_delete->next;        delete node_delete;    }    else        cout << "删除失败:链表中不存在值等于" << val << "的节点" << endl;    return;}//函数:合并两个已排序的链表(递归方法实现)link_list_t merge_linklist_recursive(link_list_t head1,link_list_t head2){    if(NULL == head1)        return head2;    else if(NULL == head2)        return head1;    link_list_t merge_head = NULL;    if(head1->m_val < head2->m_val){        merge_head = head1;        merge_head->next = merge_linklist_recursive(head1->next,head2);    }    else{        merge_head = head2;        merge_head->next = merge_linklist_recursive(head1,head2->next);    }    return merge_head;}测试平台：WIn8+Ubuntu12.04+Vim+G++：
运行结果：