在写二叉树时经常希望把它可视化，本文实现了相对直观地打印二叉树。
主要思路：
空节点使用 n (null)表示通过节点的层数计算间隔
效果图如下:
代码实现:
using System;
using System.Collections.Generic;
namespace PrintBT {
public class BinaryTree {
public class Node {
public int data;
public Node left;
public Node right;
}
static bool IsAllElementsNull(Queue<Node> queue) {
foreach (Node node
in queue) {
if (
null != node)
return false;
}
return true;
}
public static int GetDepth(Node root) {
if (root ==
null)
return 0;
int depth1 = GetDepth(root.right);
int depth2 = GetDepth(root.left);
if (depth1 > depth2)
return depth1 +
1;
else
return depth2 +
1;
}
public static void PrintSpaces(
int num) {
for (
int i =
0; i < num; ++i)
Console.Write(
" ");
}
public static void PrintNumPre(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel -
1;
if (pow >=
0) {
int num =
3 * (
int)Math.Pow(
2, pow);
PrintSpaces(num);
}
else
PrintSpaces(
1);
}
public static void PrintSymbolPre(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel -
2;
if (pow >=
0) {
int num =
3 * (
int)Math.Pow(
2, pow);
PrintSpaces(num +
1);
}
else
PrintSpaces(
2);
}
public static void PrintNumLR(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel;
int num =
3;
if (pow >
0) {
num =
3 * (
int)Math.Pow(
2, pow) -
1;
}
PrintSpaces(num);
}
public static void PrintNumRL(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel;
int num =
1;
if (pow >
0) {
num =
3 * (
int)Math.Pow(
2, pow) -
1;
}
PrintSpaces(num);
}
public static void PrintSymbolLR(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel -
1;
int num =
3;
if (pow >
0) {
num =
3 * (
int)Math.Pow(
2, pow) -
1;
}
num = num -
2;
PrintSpaces(num);
}
public static void PrintSymbolRL(
int curLevel,
int maxLevel) {
int pow = maxLevel - curLevel -
1;
int num =
1;
if (pow >
0) {
num =
3 * (
int)Math.Pow(
2, pow) -
1;
}
num = num +
2;
PrintSpaces(num);
}
public static void PrintLeft() {
Console.Write(
"/");
}
public static void PrintRight() {
Console.Write(
"\\");
}
public static void PrintQueue(Queue<Node> queueR, Queue<Node> queueW,
int level,
int maxLevel) {
if (queueR.Count ==
0 || IsAllElementsNull(queueR))
return;
level++;
Node curNode;
int index =
0;
Console.ForegroundColor = ConsoleColor.Yellow;
PrintNumPre(level, maxLevel);
Queue<Node> queueT =
new Queue<Node>();
while (queueR.Count >
0) {
curNode = queueR.Dequeue();
queueT.Enqueue(curNode);
++index;
if (
null != curNode) {
queueW.Enqueue(curNode.left);
queueW.Enqueue(curNode.right);
}
else {
queueW.Enqueue(
null);
queueW.Enqueue(
null);
}
if (
null != curNode) {
Console.Write(curNode.data);
}
else {
ConsoleColor curColor = Console.ForegroundColor;
Console.ForegroundColor = ConsoleColor.Gray;
Console.Write(
"n");
Console.ForegroundColor = curColor;
}
if (index %
2 ==
0) {
Console.ForegroundColor = ConsoleColor.Yellow;
PrintNumRL(level, maxLevel);
}
else {
Console.ForegroundColor = ConsoleColor.Green;
PrintNumLR(level, maxLevel);
}
}
if (!IsAllElementsNull(queueW)) {
Console.Write(
"\n");
PrintSymbolPre(level, maxLevel);
while (queueT.Count >
0) {
curNode = queueT.Dequeue();
PrintLeft();
PrintSymbolLR(level, maxLevel);
PrintRight();
PrintSymbolRL(level, maxLevel);
}
}
Console.Write(
"\n");
PrintQueue(queueW, queueR, level, maxLevel);
}
public static void PrintBinaryTree(Node root) {
if (
null == root)
return;
Queue<Node> queue1 =
new Queue<Node>();
Queue<Node> queue2 =
new Queue<Node>();
int maxLevel = GetDepth(root);
queue1.Enqueue(root);
PrintQueue(queue1, queue2,
0, maxLevel);
}
static void Main(
string[] args) {
Node root1 =
new Node();
root1.data =
1;
root1.left =
new Node();
root1.left.data =
2;
root1.right =
new Node();
root1.right.data =
3;
root1.left.left =
new Node();
root1.left.left.data =
4;
root1.left.right =
new Node();
root1.left.right.data =
5;
root1.right.left =
new Node();
root1.right.left.data =
6;
root1.right.right =
new Node();
root1.right.right.data =
7;
root1.left.left.left =
new Node();
root1.left.left.left.data =
8;
root1.right.right.right =
new Node();
root1.right.right.right.data =
9;
PrintBinaryTree(root1);
Node root2 =
new Node();
root2.data =
1;
root2.right =
new Node();
root2.right.data =
2;
root2.right.right =
new Node();
root2.right.right.data =
3;
root2.right.right.right =
new Node();
root2.right.right.right.data =
4;
root2.right.right.right.right =
new Node();
root2.right.right.right.right.data =
5;
Console.WriteLine(
"\n");
PrintBinaryTree(root2);
Console.ReadKey();
}
}
}
如有错误，欢迎指出。
email：dxmdxm1992#gmail.com
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