數據結構棧的java實現

時間 2019-11-30

標籤數據結構 java 實現欄目 Java 简体版

原文原文鏈接

近來複習數據結構，本身動手實現了棧。棧是一種限制插入和刪除只能在一個位置上的表。最基本的操做是進棧和出棧，所以，又被叫做「先進後出」表。java

實現方式是這樣的：首先定義了一個接口，而後經過這個接口實現了線性棧和鏈式棧，代碼比較簡單，以下：數組

 1 package com.peter.java.dsa.interfaces;
 2 
 3 /**
 4  * 棧操做定義
 5  * 
 6  * @author Peter Pan
 7  */
 8 
 9 public interface Stack<T> {
10     /* 判空 */
11     boolean isEmpty();
12 
13     /* 清空棧 */
14     void clear();
15 
16     /* 彈棧 */
17     T pop();
18 
19     /* 入棧 */
20     boolean push(T data);
21 
22     /* 棧的長度 */
23     int length();
24 
25     /* 查看棧頂的元素，但不移除它 */
26     T peek();
27 
28     /* 返回對象在棧中的位置 */
29     int search(T data);
30 }

View Code

線性棧：以數組的方式實現。數據結構

  1 package com.peter.java.dsa.common;
  2 
  3 import com.peter.java.dsa.interfaces.Stack;
  4 
  5 /**
  6  * 線性棧
  7  * 
  8  * @author Peter Pan
  9  */
 10 public class LinearStack<T> implements Stack<T> {
 11     @SuppressWarnings("unchecked")
 12     private T[] t = (T[]) new Object[16];
 13     private int size = 0;
 14 
 15     @Override
 16     public boolean isEmpty() {
 17         // TODO Auto-generated method stub
 18         return size == 0;
 19     }
 20 
 21     @Override
 22     public void clear() {
 23         // TODO Auto-generated method stub
 24         for (int i = 0; i < t.length; i++) {
 25             t[i] = null;
 26         }
 27         size = 0;
 28     }
 29 
 30     @Override
 31     public T pop() {
 32         // TODO Auto-generated method stub
 33         if (size == 0) {
 34             return null;
 35         }
 36         T tmp = t[size - 1];
 37         t[size - 1] = null;
 38         size--;
 39         return tmp;
 40     }
 41 
 42     @Override
 43     public boolean push(T data) {
 44         // TODO Auto-generated method stub
 45         if (size >= t.length) {
 46             resize();
 47         }
 48         t[size++] = data;
 49         return true;
 50     }
 51 
 52     @Override
 53     public int length() {
 54         // TODO Auto-generated method stub
 55         return size;
 56     }
 57 
 58     @Override
 59     public T peek() {
 60         // TODO Auto-generated method stub
 61         if (size == 0) {
 62             return null;
 63         } else {
 64             return t[size - 1];
 65         }
 66     }
 67 
 68     /* return index of data, return -1 if no data */
 69     @Override
 70     public int search(T data) {
 71         // TODO Auto-generated method stub
 72         int index = -1;
 73         for (int i = 0; i < t.length; i++) {
 74             if (t[i].equals(data)) {
 75                 index = i;
 76                 break;
 77             }
 78         }
 79         return index;
 80     }
 81 
 82     @SuppressWarnings("unchecked")
 83     private void resize() {
 84         T[] tmp = (T[]) new Object[t.length * 2];
 85         for (int i = 0; i < t.length; i++) {
 86             tmp[i] = t[i];
 87             t[i] = null;
 88         }
 89         t = tmp;
 90         tmp = null;
 91     }
 92 
 93     /* from the left to the right is from the top to the bottom of the stack */
 94     @Override
 95     public String toString() {
 96         // TODO Auto-generated method stub
 97         StringBuffer buffer = new StringBuffer();
 98         buffer.append("Linear Stack Content:[");
 99         for (int i = t.length - 1; i > -1; i--) {
100             buffer.append(t[i].toString() + ",");
101         }
102         buffer.append("]");
103         buffer.replace(buffer.lastIndexOf(","), buffer.lastIndexOf(",") + 1, "");
104         return buffer.toString();
105     }
106 
107 }

View Code

鏈式棧：經過單鏈表進行實現。app

  1 package com.peter.java.dsa.common;
  2 
  3 import com.peter.java.dsa.interfaces.Stack;
  4 
  5 public class LinkedStack<T> implements Stack<T> {
  6     private Node top;
  7     private int size;
  8 
  9     @Override
 10     public boolean isEmpty() {
 11         // TODO Auto-generated method stub
 12         return size == 0;
 13     }
 14 
 15     @Override
 16     public void clear() {
 17         // TODO Auto-generated method stub
 18         top = null;
 19         size = 0;
 20     }
 21 
 22     @Override
 23     public T pop() {
 24         // TODO Auto-generated method stub
 25         T topValue = null;
 26         if (top != null) {
 27             topValue = top.data;
 28             Node oldTop = top;
 29             top = top.prev;
 30             oldTop.prev = null;
 31             size--;
 32         }
 33         return topValue;
 34     }
 35 
 36     @Override
 37     public boolean push(T data) {
 38         // TODO Auto-generated method stub
 39         Node oldTop = top;
 40         top = new Node(data);
 41         top.prev = oldTop;
 42         size++;
 43         return true;
 44     }
 45 
 46     @Override
 47     public int length() {
 48         // TODO Auto-generated method stub
 49         return size;
 50     }
 51 
 52     @Override
 53     public T peek() {
 54         // TODO Auto-generated method stub
 55         T topValue = null;
 56         if (top != null) {
 57             topValue = top.data;
 58         }
 59         return topValue;
 60     }
 61 
 62     @Override
 63     public int search(T data) {
 64         // TODO Auto-generated method stub
 65         int index = -1;
 66         Node tmp = top;
 67         for (int i = size - 1; i > -1; i--) {
 68             if (tmp.data.equals(data)) {
 69                 index = i;
 70                 break;
 71             } else {
 72                 tmp = tmp.prev;
 73             }
 74         }
 75         tmp = null;
 76         return index;
 77     }
 78 
 79     @Override
 80     public String toString() {
 81         // TODO Auto-generated method stub
 82         StringBuffer buffer = new StringBuffer();
 83         buffer.append("Linked Stack Content:[");
 84         Node tmp = top;
 85         for (int i = 0; i < size - 1; i++) {
 86             buffer.append(tmp.toString() + ",");
 87             tmp = tmp.prev;
 88         }
 89         tmp = null;
 90         buffer.append("]");
 91         buffer.replace(buffer.lastIndexOf(","), buffer.lastIndexOf(",") + 1, "");
 92         return super.toString();
 93     }
 94 
 95     private class Node {
 96         T data;
 97         Node prev;
 98 
 99         public Node(T data) {
100             // TODO Auto-generated constructor stub
101             this.data = data;
102         }
103     }
104 
105 }