Java实现Stack、Queue、BinaryTree
1、用数组实现Stack：
public class MyStack {private int maxSize;private Integer[] array;private int top;public MyStack(int maxSize) {this.maxSize = maxSize;this.array = new Integer[maxSize];this.top = -1;}public void push(int item) {if (isFull()) {System.out.println("Stack is full");} else {array[++top] = item;}}public Integer peek() {if (isEmpty()) {System.out.println("Stack is empty");return null;} else {return array[top];}}public Integer pop() {if (isEmpty()) {System.out.println("Stack is empty");return null;} else {return array[top--];}}public boolean isEmpty() {return top == -1;}public boolean isFull() {return top == maxSize - 1;}public static void main(String[] args) {MyStack myStack = new MyStack(10);myStack.push(1);myStack.push(3);System.out.println("peek: " + myStack.peek());myStack.push(5);System.out.println("pop: " + myStack.pop());System.out.println("peek: " + myStack.peek());myStack.push(6);System.out.println("peek: " + myStack.peek());System.out.println("pop: " + myStack.pop());System.out.println("pop: " + myStack.pop());System.out.println("pop: " + myStack.pop());System.out.println("pop: " + myStack.pop());}}public class MyQueue {private int maxSize;private Integer[] array;private int front;private int rear;private int itemCount;public MyQueue(int maxSize) {this.maxSize = maxSize;this.array = new Integer[maxSize];this.front = 0;this.rear = -1;this.itemCount = 0;}public void insert(int item) {if (isFull()) {System.out.println("Queue is full");} else {if (rear == maxSize - 1) {rear = -1;}array[++rear] = item;itemCount++;}}public Integer remove() {if (isEmpty()) {System.out.println("Queue is empty");return null;} else {int temp = array[front++];if (front == maxSize) {front = 0;}itemCount--;return temp;}}public Integer peek() {if (isEmpty()) {System.out.println("Queue is empty");return null;} else {return array[front];}}public boolean isEmpty() {return itemCount == 0;}public boolean isFull() {return itemCount == maxSize;}public static void main(String[] args) {MyQueue myQueue = new MyQueue(5);myQueue.insert(1);myQueue.insert(2);myQueue.insert(3);myQueue.insert(4);myQueue.insert(5);myQueue.insert(6);System.out.println("peek: " + myQueue.peek());myQueue.insert(5);System.out.println("remove: " + myQueue.remove());System.out.println("peek: " + myQueue.peek());myQueue.insert(6);System.out.println("peek: " + myQueue.peek());System.out.println("remove: " + myQueue.remove());System.out.println("remove: " + myQueue.remove());System.out.println("peek: " + myQueue.peek());System.out.println("remove: " + myQueue.remove());System.out.println("remove: " + myQueue.remove());}}public class MyBinaryTree {private static class Node {int data;Node left;Node right;public Node(int data) {this.data = data;this.left = null;this.right = null;}}public Node root;public MyBinaryTree() {root = null;}private Node insert(Node node, int data) {if (node == null) {node = new Node(data);} else {if (data <= node.data) {node.left = insert(node.left, data);} else {node.right = insert(node.right, data);}}return node;}public void insert(int data) {root = insert(root, data);}public void insert(int[] data) {for (int i : data) {insert(i);}}public void preOrder(Node node) {if (node == null) {return;}System.out.println(node.data);preOrder(node.left);preOrder(node.right);}public void inOrder(Node node) {if (node == null) {return;}preOrder(node.left);System.out.println(node.data);preOrder(node.right);}public void postOrder(Node node) {if (node == null) {return;}preOrder(node.left);preOrder(node.right);System.out.println(node.data);}public static void main(String[] args) {MyBinaryTree binaryTree = new MyBinaryTree();int[] data = { 4, 8, 7, 2, 9, 3, 1, 6, 5 };binaryTree.insert(data);System.out.println("preOrder:");binaryTree.preOrder(binaryTree.root);System.out.println("inOrder:");binaryTree.inOrder(binaryTree.root);System.out.println("postOrder:");binaryTree.postOrder(binaryTree.root);}}