Untitled-1.java

package com.alsritter.algorithm;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

/**
 * @author alsritter
 * @version 1.0
 **/
public class CompleteBinaryTree {
    public static void main(String[] args) {

        int[] array = new int[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13};
        TreeNode root = Tool.createTree(array);
        Print.PrintTreeNode(root);
    }

    static class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode(int x) {
            val = x;
        }
    }


    static class Tool {
        /* * 构建完全二叉树 */
        public static TreeNode createTree(int[] array) {
            List<TreeNode> nodeList = new LinkedList<>();

            for (int nodeIndex = 0; nodeIndex < array.length; nodeIndex++) {
                nodeList.add(new TreeNode(array[nodeIndex]));
            }
            for (int parentIndex = 0; parentIndex <= array.length / 2 - 1; parentIndex++) {
                nodeList.get(parentIndex).left = nodeList.get(parentIndex * 2 + 1);
                //防止是非完全二叉树
                if ((parentIndex * 2 + 2) < array.length) {
                    nodeList.get(parentIndex).right = nodeList.get(parentIndex * 2 + 2);
                }
            }
            return nodeList.get(0);
        }
    }

    static class Print {
        //打印TreeNode
        public static void PrintTreeNode(TreeNode root) {
            ArrayList arrayList = PrintFromTopToBottom(root);
            printTree(arrayList, arrayList.size());
        }

        //转换TreeNode为ArrayList
        private static ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {

            ArrayList<Integer> list = new ArrayList();
            if (root == null)
                return list;

            Queue<TreeNode> queue = new LinkedList();
            queue.offer(root);

            while (!queue.isEmpty()) {
                TreeNode treeNode = queue.poll();
                list.add(treeNode.val);
                if (treeNode.left != null)
                    queue.offer(treeNode.left);
                if (treeNode.right != null)
                    queue.offer(treeNode.right);
            }

            return list;
        }

        //以树形打印ArrayList
        private static void printTree(ArrayList array, int len) {

            int layers = (int) Math.floor(Math.log((double) len) / Math.log((double) 2)) + 1;  //树的层数
            int maxWidth = (int) Math.pow(2, layers) - 1;  //树的最大宽度
            int endSpacing = maxWidth;
            int spacing;
            int numberOfThisLayer;
            for (int i = 1; i <= layers; i++) {  //从第一层开始，逐层打印
                endSpacing = endSpacing / 2;  //每层打印之前需要打印的空格数
                spacing = 2 * endSpacing + 1;  //元素之间应该打印的空格数
                numberOfThisLayer = (int) Math.pow(2, i - 1);  //该层要打印的元素总数

                int j;
                for (j = 0; j < endSpacing; j++) {
                    System.out.print("  ");
                }

                int beginIndex = (int) Math.pow(2, i - 1) - 1;  //该层第一个元素对应的数组下标
                for (j = 1; j <= numberOfThisLayer; j++) {
                    System.out.print(array.get(beginIndex++) + "");
                    for (int k = 0; k < spacing; k++) {  //打印元素之间的空格
                        System.out.print("  ");
                    }
                    if (beginIndex == len) {  //已打印到最后一个元素
                        break;
                    }
                }

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

    }
}