网上绝大部分的二叉树打印效果都十分潦草，也不够直观形象，最近自己用JS写了个图形化小工具BinaryTreeGraph，也用Java写了个打印器BinaryTreePrinter，还有个Objective-C版本BinaryTreePrinterOC
具体代码实现请看github
BinaryTreeGraph(JS版)
BinaryTreePrinter(Java版)
简介
树状打印一棵二叉树
比如输入一棵二叉搜索树
[381, 12, 410, 9, 40, 394, 540, 35, 190, 476, 760, 146, 445, 600, 800]
就会输出
或者输出
核心API
public final class BinaryTrees {
// 打印一棵二叉树
public static void print(BinaryTreeInfo tree);
public static void print(BinaryTreeInfo tree, PrintStyle style);
// 打印一棵二叉树(打印完自动换行)
public static void println(BinaryTreeInfo tree);
public static void println(BinaryTreeInfo tree, PrintStyle style);
// 获得一棵二叉树的打印字符串
public static String printString(BinaryTreeInfo tree);
public static String printString(BinaryTreeInfo tree, PrintStyle style);
// 可选的打印样式
public enum PrintStyle {
LEVEL_ORDER,
INORDER
}
}
示例
实现BinaryTreeInfo
根节点是谁？
如何查找左节点？
如何查找右节点？
如何打印单个节点？
/**
* BinarySearchTree是你自己编写的二叉树类
*/
public class BinarySearchTree implements BinaryTreeInfo {
/**这里省略了大量代码，只贴出了脉络代码**/
private Node root;
private static class Node {
E element;
Node left;
Node right;
}
/********** BinaryTreeInfo **********/
@Override
public Object root() {
// 根节点是谁？
return root;
}
@Override
public Object left(Object node) {
// 如何查找左节点？
return ((Node) node).left;
}
@Override
public Object right(Object node) {
// 如何查找右节点？
return ((Node) node).right;
}
@Override
public Object string(Object node) {
// 如何打印单个节点？
return ((Node) node).element;
}
/********** BinaryTreeInfo **********/
}
打印
// 随机生成的一棵二叉搜索树(random generation)
BinarySearchTree bst = ...;
// PrintStyle.LEVEL_ORDER(层序打印)
BinaryTrees.println(bst);
// PrintStyle.INORDER(中序打印)
BinaryTrees.println(bst, PrintStyle.INORDER);
生成字符串写入文件
Files.writeToFile("F:/test/bst.txt", BinaryTrees.printString(bst));
不需要定义二叉树类
BinaryTrees.println(new BinaryTreeInfo() {
@Override
public Object root() {
return 8;
}
@Override
public Object left(Object node) {
if (node.equals(8)) return 3;
if (node.equals(3)) return 1;
if (node.equals(6)) return 4;
if (node.equals(14)) return 13;
return null;
}
@Override
public Object right(Object node) {
if (node.equals(8)) return 10;
if (node.equals(10)) return 14;
if (node.equals(3)) return 6;
if (node.equals(6)) return 7;
return null;
}
@Override
public Object string(Object node) {
return node;
}
});
BinaryTrees.println(new BinaryTreeInfo() {
@Override
public Object root() {
return "Life";
}
@Override
public Object left(Object node) {
if (node.equals("Life")) return "Animal";
if (node.equals("Person")) return "Man";
if (node.equals("Animal")) return "Cat";
if (node.equals("Dog")) return "Teddy";
return null;
}
@Override
public Object right(Object node) {
if (node.equals("Life")) return "Person";
if (node.equals("Person")) return "Woman";
if (node.equals("Animal")) return "Dog";
if (node.equals("Dog")) return "SingleDog";
return null;
}
@Override
public Object string(Object node) {
return node;
}
});
二叉堆
public class BinaryHeap implements BinaryTreeInfo {
private int size;
private E[] elements;
@Override
public Object root() {
return 0;
}
@Override
public Object left(Object node) {
int index = ((int) node << 1) + 1;
return index >= size ? null : index;
}
@Override
public Object right(Object node) {
int index = ((int) node << 1) + 2;
return index >= size ? null : index;
}
@Override
public Object string(Object node) {
return elements[(int) node];
}
}
BinaryHeap heap = new BinaryHeap<>();
for (int i = 0; i < 10; i++) {
heap.add((int) (Math.random() * 100));
}
BinaryTrees.println(heap);
BinaryTreePrinterOC
实现MJBinaryTreeInfo协议
@interface MJBSTNode : NSObject {
@public
id _element;
MJBSTNode *_left;
MJBSTNode *_right;
}
@end
@interface MJBinarySearchTree : NSObject
@end
@interface MJBinarySearchTree() {
MJBSTNode *_root;
}
@end
@implementation MJBinarySearchTree
#pragma mark - MJBinaryTreeInfo
- (id)left:(MJBSTNode *)node {
return node->_left;
}
- (id)right:(MJBSTNode *)node {
return node->_right;
}
- (id)string:(MJBSTNode *)node {
return node->_element;
}
- (id)root {
return _root;
}
@end
打印
[MJBinaryTrees println:bst];
[MJBinaryTrees println:bst style:MJPrintStyleLevelOrder];
[MJBinaryTrees println:bst style:MJPrintStyleInorder];
NSString *str = [MJBinaryTrees printString:bst];
NSString *file = @"/Users/mj/Desktop/1.txt";
[str writeToFile:file atomically:YES encoding:NSUTF8StringEncoding error:nil];