栈和队列的一些基础操作

import java.util.Arrays;
class SeqStack{
// 存储栈的元素的数组
private T[] stack;
// top表示栈顶的位置
private int top;
public SeqStack(){
this(10);
}

public SeqStack(int size){
    this.stack = (T[])new Object[size];
    this.top = 0;
}
public void push(T val){
    if(full()){
        // 栈如果满了，要进行内存2倍扩容
        this.stack = Arrays.copyOf(this.stack,
                this.stack.length*2);
    }
    this.stack[this.top] = val;
    this.top++;
}

public int pop(){
    if(empty())
        return 0;
    this.top--;
    if(this.top < this.stack.length/2){
        this.stack = Arrays.copyOf(this.stack, this.stack.length/2);
    }
}

public T top(){
    return this.stack[this.top - 1];
}

public boolean full(){
    return this.top == this.stack.length;
}

public boolean empty(){
    return this.top == 0;
}

import java.util.Arrays;

/**

• 循环队列 特点：先入先出、后入后出
  */
  class Queue{
  // 存储队列元素的数组
  private E[] que;
  // 表示队头的位置
  private int front;
  // 表示队尾的位置
  private int rear;

  /**

  • 默认构造队列，初始大小是10
    */
    public Queue(){
    this(10);
    }

  /**

  • 用户可以指定队列的大小size
  • @param size
    */
    public Queue(int size){
    this.que = (E[])new Object[size];
    this.front = this.rear = 0;
    }

  /**

  • 入队操作
  • @param val
    /
    public void offer(E val){
    if(full()){
    // 扩容
    E[] newQue = Arrays.copyOf(this.que,
    this.que.length2);
    int index = 0;
    for(int i=this.front;
    i != this.rear;
    i=(i+1)%this.que.length){
    newQue[index++] = this.que[i];
    }
    this.front = 0;
    this.rear = index;
    this.que = newQue;
    }
    this.que[this.rear] = val;
    this.rear = (this.rear+1)%this.que.length;
    }

  /**

  • 出队操作，并把出队的元素的值返回
    */
    public E poll(){
    if(empty()){
    return null;
    }
    E front = this.que[this.front];
    this.front = (this.front+1)%this.que.length;
    return front;
    }

  /**

  • 查看队头元素
  • @return
    */
    public E peek(){
    if(empty()){
    return null;
    }
    return this.que[this.front];
    }

  /**

  • 判断队满
  • @return
    */
    public boolean full(){
    return (this.rear+1)%this.que.length == this.front;
    }

  /**

  • 判断队空
  • @return
    */
    public boolean empty(){
    return this.rear == this.front;
    }
    }