Merge pull request apachecn#292 from royIdoodle/master

094. Binary Tree Inorder Traversal

docs/Algorithm/Leetcode/JavaScript/0094._Binary_Tree_Inorder_Traversal.md

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+# 094. Binary Tree Inorder Traversal
+
+**<font color=orange>难度: Medium</font>**
+
+## 刷题内容
+
+> 原题连接
+
+* [https://leetcode-cn.com/problems/binary-tree-inorder-traversal/](https://leetcode-cn.com/problems/binary-tree-inorder-traversal/)
+
+> 内容描述
+
+给定一个二叉树，返回它的*中序* 遍历。
+
+**示例:**
+
+```
+输入: [1,null,2,3]
+   1
+    \
+     2
+    /
+   3
+
+输出: [1,3,2]
+```
+
+
+## 解题方案
+
+> 思路 1 迭代
+> **- 时间复杂度: O(3N)** 
+>
+> **- 空间复杂度: O(N)**
+
+> 执行用时 :**64 ms**, 在所有 JavaScript 提交中击败了**97.85%**的用户
+>
+> 内存消耗 :**33.7 MB**, 在所有 JavaScript 提交中击败了**34.70%**的用户
+
+```javascript
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+const inorderTraversal = node => {
+  const valueList = []
+  forEachTree(node)
+  return valueList
+  function forEachTree (node) {
+    if (!node) {
+      return
+    }
+    forEachTree(node.left)
+    valueList.push(node.val)
+    forEachTree(node.right)
+  }
+}
+```
+
+
+
+> 思路 2 迭代
+>
+> - 时间复杂度: O(N²) 
+> -  空间复杂度: O(N²)
+
+>执行用时 :**76 ms**, 在所有 JavaScript 提交中击败了**69.05%**的用户
+>
+>内存消耗 :**33.7 MB**, 在所有 JavaScript 提交中击败了**36.57%**的用户
+
+```javascript
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+const inorderTraversal = (node) => {
+  const valList = []
+  const stack = []
+  while (node || stack.length) {
+    if (node) {
+      stack.push(node)
+      node = node.left
+    } else {
+      node = stack.pop()
+      valList.push(node.val)
+      node = node.right
+    }
+  }
+  return valList
+};
+```
+