本帖最后由 蒋映辉 于 2012-7-8 20:28 编辑
这个 百度来的
**
* 二叉树测试二叉树顺序存储在treeLine中,递归前序创建二叉树。另外还有能
* 够前序、中序、后序、按层遍历二叉树的方法以及一个返回遍历结果asString的
* 方法。
*/
public class BitTree {
public static Node2 root;
public static String asString;
//事先存入的数组,符号#表示二叉树结束。
public static final char[] treeLine = {'a','b','c','d','e','f','g',' ',' ','j',' ',' ','i','#'};
//用于标志二叉树节点在数组中的存储位置,以便在创建二叉树时能够找到节点对应的数据。
static int index;
//构造函数
public BitTree() {
System.out.print("测试二叉树的顺序表示为:");
System.out.println(treeLine);
this.index = 0;
root = this.setup(root);
}
//创建二叉树的递归程序
private Node2 setup(Node2 current) {
if (index >= treeLine.length) return current;
if (treeLine[index] == '#') return current;
if (treeLine[index] == ' ') return current;
current = new Node2(treeLine[index]);
index = index * 2 + 1;
current.left = setup(current.left);
index ++;
current.right = setup(current.right);
index = index / 2 - 1;
return current;
}
//二叉树是否为空。
public boolean isEmpty() {
if (root == null) return true;
return false;
}
//返回遍历二叉树所得到的字符串。
public String toString(int type) {
if (type == 0) {
asString = "前序遍历:\t";
this.front(root);
}
if (type == 1) {
asString = "中序遍历:\t";
this.middle(root);
}
if (type == 2) {
asString = "后序遍历:\t";
this.rear(root);
}
if (type == 3) {
asString = "按层遍历:\t";
this.level(root);
}
return asString;
}
//前序遍历二叉树的循环算法,每到一个结点先输出,再压栈,然后访问它的左子树,
//出栈,访问其右子树,然后该次循环结束。
private void front(Node2 current) {
StackL stack = new StackL((Object)current);
do {
if (current == null) {
current = (Node2)stack.pop();
current = current.right;
} else {
asString += current.ch;
current = current.left;
}
if (!(current == null)) stack.push((Object)current);
} while (!(stack.isEmpty()));
}
//中序遍历二叉树
private void middle(Node2 current) {
if (current == null) return;
middle(current.left);
asString += current.ch;
middle(current.right);
}
//后序遍历二叉树的递归算法
private void rear(Node2 current) {
if (current == null) return;
rear(current.left);
rear(current.right);
asString += current.ch;
}
}
/**
* 二叉树所使用的节点类。包括一个值域两个链域
*/
public class Node2 {
char ch;
Node2 left;
Node2 right;
//构造函数
public Node2(char c) {
this.ch = c;
this.left = null;
this.right = null;
}
//设置节点的值
public void setChar(char c) {
this.ch = c;
}
//返回节点的值
public char getChar() {
return ch;
}
//设置节点的左孩子
public void setLeft(Node2 left) {
this.left = left;
}
//设置节点的右孩子
public void setRight (Node2 right) {
this.right = right;
}
//如果是叶节点返回true
public boolean isLeaf() {
if ((this.left == null) && (this.right == null)) return true;
return false;
}
}
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