67 lines
1.9 KiB
Java
67 lines
1.9 KiB
Java
/*
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* File: binary_tree_dfs.java
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* Created Time: 2022-11-25
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* Author: Krahets (krahets@163.com)
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*/
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package chapter_tree;
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import include.*;
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import java.util.*;
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public class binary_tree_dfs {
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// 初始化列表，用于存储遍历序列
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static ArrayList<Integer> list = new ArrayList<>();
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/* 前序遍历 */
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static void preOrder(TreeNode root) {
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if (root == null) return;
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// 访问优先级：根结点 -> 左子树 -> 右子树
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list.add(root.val);
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preOrder(root.left);
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preOrder(root.right);
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}
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/* 中序遍历 */
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static void inOrder(TreeNode root) {
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if (root == null) return;
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// 访问优先级：左子树 -> 根结点 -> 右子树
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inOrder(root.left);
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list.add(root.val);
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inOrder(root.right);
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}
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/* 后序遍历 */
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static void postOrder(TreeNode root) {
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if (root == null) return;
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// 访问优先级：左子树 -> 右子树 -> 根结点
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postOrder(root.left);
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postOrder(root.right);
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list.add(root.val);
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}
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public static void main(String[] args) {
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/* 初始化二叉树 */
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// 这里借助了一个从数组直接生成二叉树的函数
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TreeNode root = TreeNode.arrToTree(new Integer[] {
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1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null});
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System.out.println("\n初始化二叉树\n");
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PrintUtil.printTree(root);
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/* 前序遍历 */
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list.clear();
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preOrder(root);
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System.out.println("\n前序遍历的结点打印序列 = " + list);
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/* 中序遍历 */
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list.clear();
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inOrder(root);
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System.out.println("\n中序遍历的结点打印序列 = " + list);
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/* 后序遍历 */
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list.clear();
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postOrder(root);
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System.out.println("\n后序遍历的结点打印序列 = " + list);
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}
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}
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