# day17-二叉树的中序遍历
给定一个二叉树的根节点 root
,返回 它的 中序 遍历 。
示例 1:
输入:root = [1,null,2,3]
输出:[1,3,2]
1
2
2
示例 2:
输入:root = []
输出:[]
1
2
2
示例 3:
输入:root = [1]
输出:[1]
1
2
2
提示:
- 树中节点数目在范围
[0, 100]
内 -100 <= Node.val <= 100
# 解法BFS
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number[]}
*/
var inorderTraversal = function(root) {
if(!root) return []
let res = [];
let stack = [];
let cur = root;
while(stack.length || cur){
// 找到最左侧那个子节点
while(cur){
stack.push(cur);
cur = cur.left;
}
cur = stack.pop();
res.push(cur.val);
cur = cur.right;
}
return res
};
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