题目
给你二叉树的根节点 root
,返回它节点值的 前序 遍历。
示例1
输入: root = [1,null,2,3]
输出: [1,2,3]
题解
比较简单,DFS直接遍历即可
前序遍历代码
var preorderTraversal = function(root) {
let list = [];
helper(root);
return list
function helper(node){
if(node === null)return
list.push(node.val)
helper(node.left)
helper(node.right)
}
};
中序遍历代码
var preorderTraversal = function(root) {
let list = [];
helper(root);
return list
function helper(node){
if(node === null)return
helper(node.left)
list.push(node.val)
helper(node.right)
}
};
后序遍历代码
var preorderTraversal = function(root) {
let list = [];
helper(root);
return list
function helper(node){
if(node === null)return
helper(node.left)
helper(node.right)
list.push(node.val)
}
};