本文主要講兩種型別的資料結構，一種是線型結構，一種是樹型結構。

一、線型結構

線型結構常見的有：線性表（陣列、連結串列）、佇列、棧

1.1、佇列

package com.my.collection;

/**
 * Created by lige on 2018/7/2.
 */
public class Queue {

    public int size =0;
    public QNode head;
    public QNode end;

    public Queue(){
    }

    /**
     * 插入到佇列末尾
     * @param o
     */
 

    public void add(Object o){
        QNode node = new QNode(o);
        if(size<=0){
            head = node;
            end = head;
            size++;
            return;
        }

        end.next = node;
        end = node;
        size++;
    }

    public void peek(){
        if(size <=0
 
){
            System.out.println("佇列為空，無法出隊！");
            return;
        }
        QNode node = head;
        head= head.next;
        size --;
    }

    public static void printQueue(Queue queue){
        QNode node = queue.head;
        StringBuilder sb = new StringBuilder();
        while(node != null
 
){
            sb.append(node.value + "-");
            node = node.next;
        }
        System.out.println(sb);
    }
    public static void main(String[] args){
        Queue queue = new Queue();
        queue.add(new Integer(5));
        queue.add(new Integer(2));
        queue.add(new Integer(3));
        queue.add(new Integer(4));
        queue.add(new Integer(9));
        queue.add(new Integer(8));
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();
        printQueue(queue);
        queue.peek();



    }

}

class QNode{
    public QNode next;
    public Object value;

    public  QNode(Object value){
        this.value =value;
    }
}

先進先出，通過連結串列實現

1.2、棧

package com.my.collection;

/**
 * Created by lige on 2018/7/2.
 */
public class Stack {

    public int size;
    public SNode top;
    public SNode down;

    public void push(Object o) {
        SNode node = new SNode(o);
        if (size <= 0) {
            top = node;
            down = node;
            size++;
            return;
        }
        node.next = top;
        top = node;
        size++;
    }

    public void pop() {
        if (size <= 0) {
            System.out.println("棧為空，無法pop！");
            return;
        }
        SNode node = top;
        top = top.next;
        size--;
    }

    public void printStack() {
        SNode index = top;
        StringBuilder b = new StringBuilder();
        while (index != null) {
            b.append(index.value + "-");
            index = index.next;
        }
        System.out.println(b.append("size:" + size));
    }

    public static void main(String[] args) {
        Stack stack = new Stack();
        stack.push(1);
        stack.printStack();
        stack.push(2);
        stack.printStack();
        stack.push(3);
        stack.printStack();
        stack.push(4);
        stack.printStack();
        stack.push(7);
        stack.printStack();
        stack.push(8);
        stack.printStack();
        stack.pop();
        stack.printStack();
        stack.pop();
        stack.printStack();
        stack.pop();
        stack.printStack();
        stack.pop();
        stack.printStack();
        stack.pop();
        stack.printStack();


    }
}

class SNode {
    public SNode next;
    public Object value;

    public SNode(Object obj) {
        this.value = obj;
    }
}

樹

完全二叉樹

package com.my.collection;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by lige on 2018/7/2.
 */
public class BTree {
    public TreeNode root;
    public List<TreeNode> nodes = new ArrayList<TreeNode>();

    public void add(Object obj){
        TreeNode node =new TreeNode(obj);
        if(null == root){
            root = node;
            nodes.add(node);
            return;
        }
        nodes.add(node);
        int index = nodes.size() -1;
        int parentIndex = (index-1) /2;
        TreeNode parent = nodes.get(parentIndex);
        if(index % 2 != 0){
            parent.leftChild = node;
        }else{
            parent.rightChild = node;
        }
    }

    public  void preSort(TreeNode root){
        if(null != root){
            System.out.print(root.value + ",");
            preSort(root.leftChild);
            preSort(root.rightChild);
        }
    }
    public static void main(String[] args){
        BTree tree = new BTree();
        tree.add(1);
        tree.add(2);
        tree.add(3);
        tree.add(4);
        tree.add(5);
        tree.add(6);
        tree.preSort(tree.nodes.get(0));
    }


}

class TreeNode{
    public Object value;
    public TreeNode leftChild;
    public TreeNode rightChild;

    public TreeNode(Object obj){
        this.value = obj;
    }
}