Java实现的二叉树常用操作【前序建树，前中后递归非递归遍历及层序遍历】

本文实例讲述了java实现的二叉树常用操作。分享给大家供大家参考，具体如下：

import java.util.arraydeque;
import java.util.queue;
import java.util.stack;
//二叉树的建树，前中后 递归非递归遍历 层序遍历
//node节点
class node {
    int element;
    node left;
    node right;
    public node() {
    }
    public node(int element) {
        this.element = element;
    }
}
// binarytree
public class tree {
    // creat tree from array
    public static node creattree(int[] data, int i) {
        if (i >= data.length || data[i] == -1)
            return null;
        node temp = new node(data[i]);
        temp.left = creattree(data, i * 2 + 1);
        temp.right = creattree(data, i * 2 + 2);
        return temp;
    }
    // pre前序遍历递归
    public static void pre(node temp) {
        if (temp == null)
            return;
        system.out.print(temp.element + " ");
        pre(temp.left);
        pre(temp.right);
    }
    // mid中序遍历递归
    public static void mid(node temp) {
        if (temp == null)
            return;
        mid(temp.left);
        system.out.print(temp.element + " ");
        mid(temp.right);
    }
    // last后序遍历递归
    public static void last(node temp) {
        if (temp == null)
            return;
        last(temp.left);
        last(temp.right);
        system.out.print(temp.element + " ");
    }
    // pre1前序遍历非递归
    public static void pre1(node temp) {
        stack<node> stack = new stack<>();
        while (temp != null || !stack.isempty()) {
            while (temp != null) {
                stack.push(temp);
                system.out.print(temp.element + " ");
                temp = temp.left;
            }
            if (!stack.isempty()) {
                temp = stack.pop().right;
            }
        }
    }
    // mid1中序遍历非递归
    public static void mid1(node temp) {
        stack<node> stack = new stack<>();
        while (temp != null || !stack.isempty()) {
            while (temp != null) {
                stack.push(temp);
                temp = temp.left;
            }
            if (!stack.isempty()) {
                temp = stack.pop();
                system.out.print(temp.element + " ");
                temp = temp.right;
            }
        }
    }
    // last1后序遍历非递归
    public static void last1(node temp) {
        stack<node> stack = new stack<>();
        stack<node> stack2 = new stack<>();
        while (temp != null || !stack.isempty()) {
            while (temp != null) {
                stack.push(temp);
                stack2.push(temp);
                temp = temp.right;
            }
            if (!stack.isempty()) {
                temp = stack.pop().left;
            }
        }
        while (!stack2.isempty())
            system.out.print(stack2.pop().element + " ");
    }
    // ceng层序遍历
    public static void ceng(node temp) {
        if (temp == null)
            return;
        queue<node> queue = new arraydeque<>();
        queue.offer(temp);
        while (!queue.isempty()) {
            temp = queue.poll();
            system.out.print(temp.element + " ");
            if (temp.left != null)
                queue.offer(temp.left);
            if (temp.right != null)
                queue.offer(temp.right);
        }
    }
    // demo
    public static void main(string[] args) {
        int[] array = { 1, 2, 3, 4, 5, 6, 7, -1, -1, 10, -1, -1, 13 };
        node tree = creattree(array, 0);
        system.out.println("测试结果：");
        pre(tree);
        system.out.println();
        pre1(tree);
        system.out.println();
        mid(tree);
        system.out.println();
        mid1(tree);
        system.out.println();
        last(tree);
        system.out.println();
        last1(tree);
        system.out.println();
        ceng(tree);
    }
}

运行结果：

更多关于java算法相关内容感兴趣的读者可查看本站专题：《java数据结构与算法教程》、《java操作dom节点技巧总结》、《java文件与目录操作技巧汇总》和《java缓存操作技巧汇总》

希望本文所述对大家java程序设计有所帮助。