Java数据结构的实现

Posted 2021-01-01 AmosWong

1.基于数组的链表

 1 package array;
 2 
 3 import java.util.Arrays;
 4 
 5 /**
 6  * 基于数组的链表
 7  * 
 8  * @author 王彪
 9  *
10  */
11 public class MyArrayList {
12     private static Object[] elements = null;
13     private static int size = 0;
14     private static final int DEFUAT_INITIAL_CAPACITY = 10;
15 
16     public MyArrayList() {
17         this(10);
18     }
19 
20     public MyArrayList(int initialCapacity) {
21         if (initialCapacity < 0) {
22             throw new IllegalArgumentException("输入容量有误");
23         }
24         elements = new Object[initialCapacity];
25     }
26 
27 //初始化数组
28     // 保存新元素
29     public void add(Object ele) {
30         // 数组的扩容问题
31         if (size == elements.length) {
32             Object[] temp = Arrays.copyOf(elements, elements.length * 2);
33             elements = temp;
34         }
35         elements[size] = ele;
36         size++;
37     }
38 
39     public Object get(int index) {
40         if (index < 0 || index >= size) {
41             throw new IllegalArgumentException("输入索引有误");
42         }
43         return elements[index];
44     }
45 
46     public void set(int index, Object newPlayerNum) {
47         if (index < 0 || index >= size) {
48             throw new IllegalArgumentException("输入索引有误");
49         }
50         elements[index] = newPlayerNum;
51     }
52 
53     public void remove(int index) {
54         if (index < 0 || index >= size) {
55             throw new IllegalArgumentException("输入索引有误");
56         }
57         for (int i = index; i < size - 1; i++) {
58             elements[i] = elements[i + 1];
59         }
60         elements[size - 1] = null;
61         size--;
62     }
63 
64     public String toString() {
65         if (elements == null) {
66             return null;
67         }
68         if (size == 0) {
69             return "[]";
70         }
71         StringBuilder sb = new StringBuilder(size * 3 + 1);
72         sb.append("[");
73         for (int i = 0; i < size; i++) {
74             sb.append(elements[i]);
75             if (i < size - 1) {
76                 sb.append(",");
77             }
78             if (i == size - 1) {
79                 sb.append("]");
80             }
81         }
82         return sb.toString();
83     }
84 
85     public int size() {
86         return size;
87     }
88 
89     public boolean isEmpty() {
90         return size == 0;
91     }
92 
93     public void clear() {
94         this.elements = new Object[DEFUAT_INITIAL_CAPACITY];
95         size = 0;
96     }
97 
98 }

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2.双向链表

 1 package linked;
 2 
 3 public class MyLinkedArrayList {
 4     protected Node first;
 5     protected Node last;
 6     protected int size;
 7 
 8     public void addFirst(Object ele) {// 在头部增加
 9         Node node = new Node(ele);
10         if (size == 0) {
11             this.first = node;
12             this.last = node;
13         } else {
14             node.next = this.first;
15             this.first.prev = node;
16             this.first = node;
17         }
18         size++;
19     }
20 
21     public void addLast(Object ele) {// 在尾部增加
22         Node node = new Node(ele);
23         if (size == 0) {
24             this.first = node;
25             this.last = node;
26         } else {
27             this.last.next = node;
28             node.prev = this.last;
29             this.last = node;
30         }
31         size++;
32     }
33 
34     public void remove(Object ele) {
35         Node current = this.first;
36         for (int i = 0; i < size; i++) {
37             if (!current.ele.equals(ele)) {
38                 if (current.next == null) {
39                     return;
40                 }
41                 current = current.next;
42             }
43         }
44         if (current == this.first) {
45             this.first = current.next;
46             this.first.prev = null;
47         } else if (current == this.last) {
48             this.last = current.prev;
49             this.last.next = null;
50         } else {
51             current.prev.next = current.next;
52             current.next.prev = current.prev;
53         }
54         size--;
55     }
56 
57     @Override
58     public String toString() {
59         if (size == 0) {
60             return "[]";
61         } else {
62             StringBuilder sb = new StringBuilder(size * 3 + 1);
63             Node current = this.first;// 第一个节点
64             sb.append("[");
65             for (int i = 0; i < size; i++) {
66                 sb.append(current.ele);
67                 if (i != size - 1) {
68                     sb.append(",");
69                 } else {
70                     sb.append("]");
71                 }
72                 current = current.next;
73             }
74             return sb.toString();
75         }
76     }
77 
78     public class Node {
79         public Node(Object ele) {
80             this.ele = ele;
81         }
82 
83         Node prev;
84         Node next;
85         public Object ele;
86     }
87 }

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3.双向队列

 1 package deque;
 2 
 3 import linked.MyLinkedArrayList;
 4 
 5 public class MyDeque extends MyLinkedArrayList {
 6     public Object getFirst() {
 7         return this.first.ele;
 8     }
 9 
10     public Object getLast() {
11         return this.last.ele;
12     }
13 
14     public void removeFirst(Object ele) {
15         super.remove(this.first);
16     }
17 
18     public void removeLast(Object ele) {
19         super.remove(this.last);
20     }
21 
22     public void addFirst(Object ele) {
23         super.addFirst(ele);
24     }
25 
26     public void addLast(Object ele) {
27         super.addLast(ele);
28     }
29 
30 }

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4.堆

 1 package stack;
 2 
 3 import array.MyArrayList;
 4 
 5 //栈
 6 public class MyStack extends MyArrayList {
 7     // 入栈
 8     public void push(Object ele) {
 9         super.add(ele);
10     }
11 
12     // 删除栈顶元素
13     public void pop() {
14         int index = super.size() - 1;
15         super.remove(index);
16     }
17 
18     // 查询栈顶元素
19     public Object peek() {
20         int index = super.size() - 1;
21         return super.get(index);
22     }
23 
24 }