双向链表的基本操作

  1 #include "iostream"
  2 #include "stdlib.h"
  3 
  4 /*宏函数*/
  5 #define log(data) std::cout<<data<<std::endl
  6 
  7 #define isNull(ptr);  8 {  9     if(ptr==nullptr){ 10         log("链表为空"); 11         return; } 12 } 13 
 14 typedef struct _node_
 15 {
 16     int data;
 17     struct _node_ *pre;
 18     struct _node_ *next;
 19 }node;
 20 
 21 /*在尾部加入新节点*/
 22 void addToTail(node *&head,node *&tail, int data)
 23 {
 24     node *p = (node *)malloc(sizeof(node));
 25     p->data = data;
 26     p->pre = nullptr;
 27     p->next= nullptr;
 28     if (tail == nullptr)
 29     {
 30         head = p;
 31         tail = p;
 32     }
 33     else
 34     {
 35         p->pre = tail;
 36         tail->next = p;
 37         tail = p;
 38     }
 39 }
 40 
 41 /*指定位置插入*/
 42 void insertByIndex(node *&head, node *&tail, int index, int data)
 43 {
 44     node *tmp,*bak = head;/*备份头部*/
 45 
 46     int num = 1;
 47 
 48     node *p = (node *)malloc(sizeof(node));
 49     p->data = data;
 50     p->pre = nullptr;
 51     p->next = nullptr;
 52 
 53     if (head == nullptr)
 54     {
 55         if (index == 1)
 56         {
 57             head = tail = p;
 58         }
 59         else
 60         {
 61             free(p);
 62             std::cout << "链表为空，仅支持从索引 1 处插入数据" << std::endl;
 63         }
 64         return;
 65     }
 66 
 67     while (head != tail && index != num)
 68     {
 69         head = head->next;
 70         ++num;
 71     }
 72 
 73     if (index != num)
 74     {
 75         std::cout << "索引越界" << std::endl;
 76         free(p);
 77         head = bak;
 78         return;
 79     }
 80 
 81     p->pre = head->pre;
 82     p->next = head;
 83     head->pre->next = p;
 84     head->pre = p;
 85 
 86     head = bak;
 87 }
 88 
 89 /*前序遍历*/
 90 void forDisplay(node *head,node *tail)
 91 {
 92     isNull(head);
 93     while (head != tail)
 94     { 
 95         std::cout << head->data << std::endl;
 96         head=head->next;
 97     }
 98     std::cout << head->data << std::endl;
 99     std::cout << "==END==" << std::endl;
100 }
101 
102 /*倒序遍历*/
103 void backDisplay(node *head, node *tail)
104 {
105     isNull(head);
106     while (tail!=head)
107     {
108         std::cout << tail->data << std::endl;
109         tail = tail->pre;
110     }
111     std::cout << tail->data << std::endl;
112     std::cout << "==END==" << std::endl;
113 }
114 
115 /*删除第一个匹配的节点*/
116 void deleteData(node *&head, node *&tail,int data)
117 {
118     isNull(head);
119     node *tmp, *bak = head;
120     if (head->data == data)
121     {
122         tmp = head;
123         head = head->next;
124         free(tmp);
125         return;
126     }
127     head = head->next;
128     while (head != tail && head->data!=data)
129     {
130         head = head->next;
131     }
132 
133     if (head->next==nullptr)
134     {
135         tmp = tail;
136         tail = tail->pre;
137         tail->next = nullptr;
138         free(tmp);
139     }
140     else
141     {
142         head->pre->next = head->next;
143         head->next->pre = head->pre;
144         free(head);
145     }
146     head = bak;
147 }
148 
149 /*删除指定位置的节点*/
150 void deleteByIndex(node *&head, node *&tail, int index)
151 {
152     isNull(head);
153     node *tmp, *bak = head;
154     int num = 2;
155     if (index == 1)
156     {
157         tmp = head;
158         head = head->next;
159         free(tmp);
160         return;
161     }
162     head = head->next;
163     while (head != tail && index != num)
164     {
165         ++num;
166         head = head->next;
167     }
168 
169     if (index != num)
170     {
171         std::cout << "索引越界，最大应为"<< num << std::endl;
172         head = bak;
173         return;
174     }
175 
176     if (head->next == nullptr)
177     {
178         tail = tail->pre;
179         tail->next = nullptr;
180         free(head);
181         head = bak;
182         return;
183     }
184 
185     head->pre->next = head->next;
186     head->next->pre = head->pre;
187     free(head);
188     head = bak;
189 }
190 
191 int main(void)
192 {
193     node *head=nullptr;
194     node *tail = nullptr;
195 
196     addToTail(head, tail, 1);
197     addToTail(head, tail, 2);
198     addToTail(head, tail, 3);
199     addToTail(head, tail, 4);
200     addToTail(head, tail, 5);
201 
202     insertByIndex(head, tail, 2, 123);
203     forDisplay(head, tail);
204 
205     deleteByIndex(head, tail, 3);
206     forDisplay(head, tail);
207     system("pause");
208     return 0;
209 }