ADT：
/**
* see if Steque is empty
* @return {@code true} Steque is empty
* {@code false} Steque isn‘t empty
*/
public boolean isEmpty()
/**
* return the size of the Steque
* @return return the size of the Steque
*/
public int size()
/**
* push one item at the beginning of the steque
*
* @param item the item to be pushed
*/
public void push(Item item)
/**
* pop one item at the beginning of the steque
*
* @return return the item at the beginning of the steque
* @throws NoSuchElementException if the steque is empty
*/
public Item pop()
/**
* enqueue one item at the end of the steque
* @param item the item to be enqueued
*/
public void enqueue(Item item)
代码实现以及测试：
package com.qiusongde.creative;
import java.util.Iterator;
import java.util.NoSuchElementException;
import edu.princeton.cs.algs4.StdOut;
public class Steque<Item> implements Iterable<Item> {
private Node<Item> first;
private Node<Item> last;
private int size;
public Steque() {
first = null;
last = null;
size = 0;
}
private class Node<E> {
E item;
Node<E> next;
}
/**
* see if Steque is empty
* @return {@code true} Steque is empty
* {@code false} Steque isn‘t empty
*/
public boolean isEmpty() {
return first == null;
}
/**
* return the size of the Steque
* @return return the size of the Steque
*/
public int size() {
return size;
}
/**
* push one item at the beginning of the steque
*
* @param item the item to be pushed
*/
public void push(Item item) {
Node<Item> oldfirst = first;
first = new Node<Item>();
first.item = item;
first.next = oldfirst;
if(oldfirst == null) {
last = first;
}
size++;
}
/**
* pop one item at the beginning of the steque
*
* @return return the item at the beginning of the steque
* @throws NoSuchElementException if the steque is empty
*/
public Item pop() {
if(isEmpty())
throw new NoSuchElementException("Steque is empty");
Item item = first.item;
first = first.next;
if(isEmpty())
last = null;
size--;
return item;
}
/**
* enqueue one item at the end of the steque
* @param item the item to be enqueued
*/
public void enqueue(Item item) {
Node<Item> oldlast = last;
last = new Node<Item>();
last.item = item;
last.next = null;
if(oldlast == null)
first = last;
else
oldlast.next = last;
size++;
}
@Override
public String toString() {
String s = "";
Node<Item> current = first;
while(current != null) {
s += current.item + " ";
current = current.next;
}
s += first == null ? "first:null " : "first:" + first.item + " ";
s += last == null ? "last:null " : "last:" + last.item + " ";
return s;
}
@Override
public Iterator<Item> iterator() {
return new StequeIterator();
}
private class StequeIterator implements Iterator<Item> {
private Node<Item> current = first;
@Override
public boolean hasNext() {
return current != null;
}
@Override
public Item next() {
if(!hasNext())
throw new NoSuchElementException("Steque is empty");
Item item = current.item;
current = current.next;
return item;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
public static void main(String[] args) {
Steque<Integer> steque = new Steque<Integer>();
StdOut.println("Initial steque:");
StdOut.println(steque);
StdOut.println();
//test push function
StdOut.println("Test push function");
for(int i = 1; i <= 10; i++) {
steque.push(i);
StdOut.println("push success: " + i);
StdOut.println(steque);
}
StdOut.println();
//test pop function
StdOut.println("Test pop function");
for(int i = 1; i <= 10; i++) {
int out = steque.pop();
StdOut.println("pop success: " + out);
StdOut.println(steque);
}
StdOut.println();
//test enqueue function
StdOut.println("Test enqueue function");
for(int i = 1; i <= 10; i++) {
steque.enqueue(i);
StdOut.println("enqueue success: " + i);
StdOut.println(steque);
}
StdOut.println();
//end
for(int i : steque) {
StdOut.print(i + " ");
}
StdOut.println();
}
}
输出结果：
Initial steque: first:null last:null Test push function push success: 1 1 first:1 last:1 push success: 2 2 1 first:2 last:1 push success: 3 3 2 1 first:3 last:1 push success: 4 4 3 2 1 first:4 last:1 push success: 5 5 4 3 2 1 first:5 last:1 push success: 6 6 5 4 3 2 1 first:6 last:1 push success: 7 7 6 5 4 3 2 1 first:7 last:1 push success: 8 8 7 6 5 4 3 2 1 first:8 last:1 push success: 9 9 8 7 6 5 4 3 2 1 first:9 last:1 push success: 10 10 9 8 7 6 5 4 3 2 1 first:10 last:1 Test pop function pop success: 10 9 8 7 6 5 4 3 2 1 first:9 last:1 pop success: 9 8 7 6 5 4 3 2 1 first:8 last:1 pop success: 8 7 6 5 4 3 2 1 first:7 last:1 pop success: 7 6 5 4 3 2 1 first:6 last:1 pop success: 6 5 4 3 2 1 first:5 last:1 pop success: 5 4 3 2 1 first:4 last:1 pop success: 4 3 2 1 first:3 last:1 pop success: 3 2 1 first:2 last:1 pop success: 2 1 first:1 last:1 pop success: 1 first:null last:null Test enqueue function enqueue success: 1 1 first:1 last:1 enqueue success: 2 1 2 first:1 last:2 enqueue success: 3 1 2 3 first:1 last:3 enqueue success: 4 1 2 3 4 first:1 last:4 enqueue success: 5 1 2 3 4 5 first:1 last:5 enqueue success: 6 1 2 3 4 5 6 first:1 last:6 enqueue success: 7 1 2 3 4 5 6 7 first:1 last:7 enqueue success: 8 1 2 3 4 5 6 7 8 first:1 last:8 enqueue success: 9 1 2 3 4 5 6 7 8 9 first:1 last:9 enqueue success: 10 1 2 3 4 5 6 7 8 9 10 first:1 last:10 1 2 3 4 5 6 7 8 9 10
时间： 2024-10-10 06:51:12