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hello-algo/codes/javascript/chapter_tree/binary_tree_dfs.js

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/**
* File: binary_tree_dfs.js
* Created Time: 2022-12-04
* Author: IsChristina (christinaxia77@foxmail.com)
*/
const { arrToTree } = require('../modules/TreeNode');
const { printTree } = require('../modules/PrintUtil');
// 初始化列表,用于存储遍历序列
const list = [];
/* 前序遍历 */
function preOrder(root) {
if (root === null) return;
// 访问优先级:根节点 -> 左子树 -> 右子树
list.push(root.val);
preOrder(root.left);
preOrder(root.right);
}
/* 中序遍历 */
function inOrder(root) {
if (root === null) return;
// 访问优先级:左子树 -> 根节点 -> 右子树
inOrder(root.left);
list.push(root.val);
inOrder(root.right);
}
/* 后序遍历 */
function postOrder(root) {
if (root === null) return;
// 访问优先级:左子树 -> 右子树 -> 根节点
postOrder(root.left);
postOrder(root.right);
list.push(root.val);
}
/* Driver Code */
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
const root = arrToTree([1, 2, 3, 4, 5, 6, 7]);
console.log('\n初始化二叉树\n');
printTree(root);
/* 前序遍历 */
list.length = 0;
preOrder(root);
console.log('\n前序遍历的节点打印序列 = ' + list);
/* 中序遍历 */
list.length = 0;
inOrder(root);
console.log('\n中序遍历的节点打印序列 = ' + list);
/* 后序遍历 */
list.length = 0;
postOrder(root);
console.log('\n后序遍历的节点打印序列 = ' + list);