笔试面试常考数据结构-单链表常用操作编程实现

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于 2013-11-07 14:40:00 发布

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分类专栏：就业指导文章标签：数据结构算法面试 C++ Linux

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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++）：

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//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(<span style="font-family: Arial, Helvetica, sans-serif;">merge_list_head</span><span style="font-family: Arial, Helvetica, sans-serif;">);</span>
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;
}