算法－第四版－练习1.3.14解答

问题

编写一个类ResizingArrayQueueOfStrings，使用定长数组实现队列的抽象，然后扩展实现，使用调整数组的方法突破大小的限制。

解决思路

参照堆栈的实现即可。

代码

/**
 * Description : 
 * Author      : mn@furzoom.com
 * Date        : Oct 20, 2016 3:15:52 PM
 * Copyright (c) 2013-2016, http://furzoom.com All Rights Reserved.
 */
package com.furzoom.lab.algs.ch103;

/**
 * ClassName    : ResizingArrayQueueOfStrings <br>
 * Function     : TODO ADD FUNCTION. <br>
 * date         : Oct 20, 2016 3:15:52 PM <br>
 * 
 * @version 
 */
public class ResizingArrayQueueOfStrings
{
    private int first;
    private int last;
    private int count;
    private String[] queue;
    
    public ResizingArrayQueueOfStrings()
    {
        first = 0;
        last = 0;
        count = 1;
        queue = new String[count];
    }
    
    public boolean isEmpty()
    {
        return first == last;
    }
    
    public int size()
    {
        return last - first;
    }
    
    public void enqueue(String s)
    {
        if (last == count) {
            resizing(2 * size());
        }
        queue[last++] = s;
    }
    
    public String dequeue()
    {
        if (size() < count / 4) {
            resizing(2 * size());
        }
        return queue[first++];
            
    }
    
    private void resizing(int n)
    {
        String[] tmp = new String[n];
        int j = 0;
        for (int i = first; i < last; i++) {
            tmp[j++] = queue[i];
        }
        queue = tmp;
        count = n;
        last = last - first;
        first = 0;
    }
    
    public static void main(String[] args) {
        ResizingArrayQueueOfStrings queue = new ResizingArrayQueueOfStrings();
        queue.enqueue("a");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("b");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("c");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("d");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("e");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("f");
        System.out.println("size(): " + queue.size() + " | count: " + queue.count);
        queue.enqueue("g");
        while (!queue.isEmpty()) {
            System.out.println(queue.dequeue() + " | size(): " + queue.size() + " | count: " + queue.count);
        }
    }
}

输出：

size(): 1 | count: 1
size(): 2 | count: 2
size(): 3 | count: 4
size(): 4 | count: 4
size(): 5 | count: 8
size(): 6 | count: 8
a | size(): 6 | count: 8
b | size(): 5 | count: 8
c | size(): 4 | count: 8
d | size(): 3 | count: 8
e | size(): 2 | count: 8
f | size(): 1 | count: 8
g | size(): 0 | count: 2

算法－第四版－1.3 背包、队列和栈－习题索引汇总

算法－第四版习题索引汇总