一个调的很好的打印二叉树的代码。

用空格和^v来表示节点之间的关系。

效果是这样：

Binary Tree:
                                         v7v       
                        v6v       
                                         ^5^       
       H4H       
                                         v3v       
                        ^2^       
                                         ^1^  

 

对于每个节点，先打印右子树，然后打印本身，然后打印左子树。

 

public class fan {public static class Node {public int value;Node left;Node right;public Node(int data) {this.value = data;}}public static void printTree(Node head) {System.out.println("Binary Tree:");printInOrder(head, 0, "H", 17);System.out.println();}public static void printInOrder(Node head, int height, String to, int len) {if (head == null) {return;}printInOrder(head.right, height + 1, "v", len);String val = to + head.value + to;int lenM = val.length();int lenL = (len - lenM) / 2;int lenR = len - lenM - lenL;val = getSpace(lenL) + val + getSpace(lenR);System.out.println(getSpace(height * len) + val);printInOrder(head.left, height + 1, "^", len);}public static String getSpace(int num) {String space = " ";StringBuffer buf = new StringBuffer("");for (int i = 0; i < num; i++) {buf.append(space);}return buf.toString();}public static void main(String[] args) {Node head = new Node(4);head.left = new Node(2);head.right = new Node(6);head.left.left = new Node(1);head.left.right = new Node(3);head.right.left = new Node(5);head.right.right = new Node(7);printTree(head);}}