Go语言视频零基础入门到精通

五菱

构造树如下:



其中二叉树节点类

/** 二叉树节点 */

public class BTNode {

private char key;

private BTNode left, right;

public BTNode(char key) {

this(key, null, null);

}

public BTNode(char key, BTNode left, BTNode right) {

this.key = key;

this.left = left;

this.right = right;

}

public char getKey() {

return key;

}

public void setKey(char key) {

this.key = key;

}

public BTNode getLeft() {

return left;

}

public void setLeft(BTNode left) {

this.left = left;

}

public BTNode getRight() {

return right;

}

public void setRight(BTNode right) {

this.right = right;

}

}

遍历二叉树

/** 二叉树遍历 */
public class BinTree {
protected BTNode root;
public BinTree(BTNode root) {
this.root = root;
}
public BTNode getRoot() {
return root;
}
/** 构造树 */
public static BTNode init() {
BTNode a = new BTNode('A');
BTNode b = new BTNode('B', null, a);
BTNode c = new BTNode('C');
BTNode d = new BTNode('D', b, c);
BTNode e = new BTNode('E');
BTNode f = new BTNode('F', e, null);
BTNode g = new BTNode('G', null, f);
BTNode h = new BTNode('H', d, g);
return h;// root
}
/** 访问节点 */
public static void visit(BTNode p) {
System.out.print(p.getKey() + " ");
}
/** 递归实现前序遍历 */
protected static void preorder(BTNode p) {
if (p != null) {
visit(p);
preorder(p.getLeft());
preorder(p.getRight());
}
}
/** 递归实现中序遍历 */
protected static void inorder(BTNode p) {
if (p != null) {
inorder(p.getLeft());
visit(p);
inorder(p.getRight());
}
}
/** 递归实现后序遍历 */
protected static void postorder(BTNode p) {
if (p != null) {
postorder(p.getLeft());
postorder(p.getRight());
visit(p);
}
}
/** 非递归实现前序遍历 */
protected static void iterativePreorder(BTNode p) {
Stack<BTNode> stack = new Stack<BTNode>();
if (p != null) {
stack.push(p);
while (!stack.empty()) {
p = stack.pop();
visit(p);
if (p.getRight() != null)
stack.push(p.getRight());
if (p.getLeft() != null)
stack.push(p.getLeft());
}
}
}
/** 非递归实现后序遍历 */
protected static void iterativePostorder(BTNode p) {
BTNode q = p;
Stack<BTNode> stack = new Stack<BTNode>();
while (p != null) {
// 左子树入栈
for (; p.getLeft() != null; p = p.getLeft())
stack.push(p);
// 当前节点无右子或右子已经输出
while (p != null && (p.getRight() == null		p.getRight() == q)) {
visit(p);
q = p;// 记录上一个已输出节点
if (stack.empty())
return;
p = stack.pop();
}
// 处理右子
stack.push(p);
p = p.getRight();
}
}
/** 非递归实现中序遍历 */
protected static void iterativeInorder(BTNode p) {
Stack<BTNode> stack = new Stack<BTNode>();
while (p != null) {
while (p != null) {
if (p.getRight() != null)
stack.push(p.getRight());// 当前节点右子入栈
stack.push(p);// 当前节点入栈
p = p.getLeft();
}
p = stack.pop();
while (!stack.empty() && p.getRight() == null) {
visit(p);
p = stack.pop();
}
visit(p);
if (!stack.empty())
p = stack.pop();
else
p = null;
}
}
public static void main(String[] args) {
BinTree tree = new BinTree(init());
System.out.print(" Pre-Order:");
preorder(tree.getRoot());
System.out.println();
System.out.print("  In-Order:");
inorder(tree.getRoot());
System.out.println();
System.out.print(&quotost-Order:");
postorder(tree.getRoot());
System.out.println();
System.out.print(" Pre-Order:");
iterativePreorder(tree.getRoot());
System.out.println();
System.out.print("  In-Order:");
iterativeInorder(tree.getRoot());
System.out.println();
System.out.print("Post-Order:");
iterativePostorder(tree.getRoot());
System.out.println();
}
}

输出结果
Pre-Order:H D B A C G F E
  In-Order:B A D C H G E F
Post-Order:A B C D E F G H
Pre-Order:H D B A C G F E
  In-Order:B A D C H G E F
Post-Order:A B C D E F G H