public class Stack {

public Node head;
 public Node current;

//方法：入棧操作
 public void push(int data) {
  if (head == null) {
   head = new Node(data);
   current = head;
  } else {
   Node node = new Node(data);
   node.pre = current;//current結點將作為當前結點的前驅結點
   current = node; //讓current結點永遠指向新添加的那個結點
  }
 }

public Node pop() {
  if (current == null) {
   return null;
  }

Node node = current; // current結點是我們要出棧的結點
  current = current.pre; //每出棧一個結點后，current后退一位
  return node;

}

class Node {
  int data;
  Node pre; //我們需要知道當前結點的前一個結點

public Node(int data) {
   this.data = data;
  }
 }

public static void main(String[] args) {

Stack stack = new Stack();
  stack.push(1);
  stack.push(2);
  stack.push(3);

System.out.println(stack.pop().data);
  System.out.println(stack.pop().data);
  System.out.println(stack.pop().data);
 }

}

public class Queue {
 public Node head;
 public Node curent;

//方法：鏈表中添加結點
 public void add(int data) {
  if (head == null) {
   head = new Node(data);
   curent = head;
  } else {
   curent.next = new Node(data);
   curent = curent.next;
  }
 }

//方法：出隊操作
 public int pop() throws Exception {
  if (head == null) {
   throw new Exception("隊列為空");
  }

Node node = head; //node結點就是我們要出隊的結點
  head = head.next; //出隊之后，head指針向下移

return node.data;

}

class Node {
  int data;
  Node next;

public Node(int data) {
   this.data = data;
  }
 }

public static void main(String[] args) throws Exception {
  Queue queue = new Queue();
  //入隊操作
  for (int i = 0; i < 5; i++) {
   queue.add(i);
  }

//出隊操作
  System.out.println(queue.pop());
  System.out.println(queue.pop());
  System.out.println(queue.pop());

}
}

import java.util.Stack;

/**
* Created by smyhvae on 2015/9/9.
*/
public class Queue {

private Stack<Integer> stack1 = new Stack<>();//執(zhí)行入隊操作的棧
 private Stack<Integer> stack2 = new Stack<>();//執(zhí)行出隊操作的棧

//方法：給隊列增加一個入隊的操作
 public void push(int data) {
  stack1.push(data);

}

//方法：給隊列正價一個出隊的操作
 public int pop() throws Exception {

if (stack2.empty()) {//stack1中的數(shù)據(jù)放到stack2之前，先要保證stack2里面是空的（要么一開始就是空的，要么是stack2中的數(shù)據(jù)出完了），不然出隊的順序會亂的，這一點很容易忘

while (!stack1.empty()) {
    stack2.push(stack1.pop());//把stack1中的數(shù)據(jù)出棧，放到stack2中【核心代碼】
   }

}

if (stack2.empty()) { //stack2為空時，有兩種可能：1、一開始，兩個棧的數(shù)據(jù)都是空的；2、stack2中的數(shù)據(jù)出完了
   throw new Exception("隊列為空");
  }

return stack2.pop();
 }

public static void main(String[] args) throws Exception {
  Queue queue = new Queue();
  queue.push(1);
  queue.push(2);
  queue.push(3);

System.out.println(queue.pop());

queue.push(4);

System.out.println(queue.pop());
  System.out.println(queue.pop());
  System.out.println(queue.pop());

}

}

import java.util.ArrayDeque;
import java.util.Queue;

/**
* Created by smyhvae on 2015/9/9.
*/
public class Stack {

Queue<Integer> queue1 = new ArrayDeque<Integer>();
 Queue<Integer> queue2 = new ArrayDeque<Integer>();

//方法：入棧操作
 public void push(int data) {
  queue1.add(data);
 }

//方法：出棧操作
 public int pop() throws Exception {
  int data;
  if (queue1.size() == 0) {
   throw new Exception("棧為空");
  }

while (queue1.size() != 0) {
   if (queue1.size() == 1) {
    data = queue1.poll();
    while (queue2.size() != 0) { //把queue2中的全部數(shù)據(jù)放到隊列一中
     queue1.add(queue2.poll());
     return data;
    }
   }
   queue2.add(queue1.poll());
  }
  throw new Exception("棧為空");//不知道這一行的代碼是什么意思
 }

public static void main(String[] args) throws Exception {
  Stack stack = new Stack();

stack.push(1);
  stack.push(2);
  stack.push(3);

System.out.println(stack.pop());
  System.out.println(stack.pop());
  stack.push(4);
 }
}

import java.util.Stack;

/**
* Created by smyhvae on 2015/9/9.
*/
public class MinStack {

private Stack<Integer> stack = new Stack<Integer>();
 private Stack<Integer> minStack = new Stack<Integer>(); //輔助棧：棧頂永遠保存stack中當前的最小的元素

public void push(int data) {
  stack.push(data); //直接往棧中添加數(shù)據(jù)

//在輔助棧中需要做判斷
  if (minStack.size() == 0 || data < minStack.peek()) {
   minStack.push(data);
  } else {
   minStack.add(minStack.peek()); //【核心代碼】peek方法返回的是棧頂?shù)脑?
  }
 }

public int pop() throws Exception {
  if (stack.size() == 0) {
   throw new Exception("棧中為空");
  }

int data = stack.pop();
  minStack.pop(); //核心代碼
  return data;
 }

public int min() throws Exception {
  if (minStack.size() == 0) {
   throw new Exception("棧中空了");
  }
  return minStack.peek();
 }

public static void main(String[] args) throws Exception {
  MinStack stack = new MinStack();
  stack.push(4);
  stack.push(3);
  stack.push(5);

System.out.println(stack.min());
 }
}