1 #pragma once
2
3 // List.h
4
5 #include <iostream>
6
7 using namespace std;
8
9 struct Node
10 {
11 int element;
12 Node *next;
13 };
14
15 class List //单向链表
16 {
17 public:
18 List();
19 bool empty() const; //检查链表是否为空
20 int front() const; //返回链表的第一个元素
21 int back() const; //返回链表的最后一个元素
22 int size() const; //返回链表的长度
23 Node* find(int ele); //返回指向ele的指针
24 void insert(int position, int ele); //在position位置插入ele (head处于position = 0的位置)
25 void push_back(int ele); //在尾部插入
26 void remove(int ele); //删除值为ele的所有元素
27 void clear(); //清空链表，有了这个操作之后就不要定义析构函数了
28 void print(); //打印链表中的所有元素
29
30 private:
31 Node *head; //头结点
32 int length; //链表长度
33 };
34
35 List::List()
36 {
37 head = new Node; //head不能是nullptr，不然head->next是未定义的行为
38 head->next = nullptr;
39 length = 0;
40 }
41
42 bool List::empty() const
43 {
44 return (head->next) == nullptr;
45 }
46
47 int List::front() const
48 {
49 return (head->next)->element;
50 }
51
52 int List::back() const
53 {
54 Node* p = head;
55 while (p->next != nullptr)
56 p = p->next;
57 return p->element;
58 }
59
60 int List::size() const
61 {
62 return length;
63 }
64
65
66 Node* List::find(int ele)
67 {
68 Node* p = head;
69 while (p->next != nullptr)
70 {
71 p = p->next;
72 if (p->element = ele)
73 return p;
74 }
75 cout << "Not find this element!" << endl;
76 return nullptr;
77 }
78
79 void List::insert(int position, int ele) //在特定位置插入元素,在position位置插入一个元素
80 {
81 Node* p = head;
82 for (int i = 1; i <= position - 1; ++i)
83 p = p->next; //获取position前一个位置的指针p
84 Node *newNode = new Node;
85 newNode->element = ele;
86 newNode->next = p->next;
87 p->next = newNode;
88 ++length;
89 }
90
91 void List::push_back(int ele)
92 {
93 Node* p = head;
94 while (p->next != nullptr)
95 p = p->next;
96 Node *newNode = new Node;
97 newNode->element = ele;
98 p->next = newNode;
99 newNode->next = nullptr;
100 ++length;
101 }
102
103 void List::remove(int ele)
104 {
105 Node *q = head;
106 auto p = q->next;
107
108 while (p != nullptr)
109 {
110 if (p->element == ele)
111 {
112 q->next = p->next;
113 delete p;
114 p = q->next;
115 --length;
116 }
117 else
118 {
119 q = p;
120 p = q->next;
121 }
122 }
123 }
124
125 void List::clear()
126 {
127 Node* p1 = head->next;
128 while (p1 != nullptr)
129 {
130 auto p2 = p1->next;
131 delete p1;
132 if (p2 != nullptr)
133 p1 = p2;
134 else break;
135 }
136 length = 0;
137 }
138
139 void List::print()
140 {
141 Node* p1 = head->next;
142 while (p1 != nullptr)
143 {
144 cout << p1->element << ' ';
145 p1 = p1->next;
146 }
147 }
1 //main.cpp
2
3 #include <iostream>
4 #include "List.h"
5
6 using namespace std;
7
8 int main()
9 {
10 List lst;
11 lst.push_back(1);
12 lst.push_back(2);
13 lst.push_back(3);
14 lst.push_back(2);
15 lst.push_back(9);
16 lst.remove(2);
17
18 cout << lst.size();
19
20
21 return 0;
22 }
