feat: update leetcode solution: No.0094

Author: yanglbme

README.md

@@ -96,6 +96,9 @@
 
 ### 二叉树
 
+- [二叉树的前序遍历](/solution/0100-0199/0144.Binary%20Tree%20Preorder%20Traversal/README.md)
+- [二叉树的后序遍历](/solution/0100-0199/0145.Binary%20Tree%20Postorder%20Traversal/README.md)
+- [二叉树的中序遍历](/solution/0000-0099/0094.Binary%20Tree%20Inorder%20Traversal/README.md)
 - [对称二叉树](/solution/0100-0199/0101.Symmetric%20Tree/README.md)
 - [树的子结构](/lcof/面试题26.%20树的子结构/README.md)
 - [翻转二叉树](/solution/0200-0299/0226.Invert%20Binary%20Tree/README.md)

README_EN.md

@@ -94,6 +94,9 @@ Complete solutions to [LeetCode](https://leetcode-cn.com/problemset/all/), [LCOF
 
 ### Binary Tree
 
+- [Binary Tree Preorder Traversal](/solution/0100-0199/0144.Binary%20Tree%20Preorder%20Traversal/README_EN.md)
+- [Binary Tree Postorder Traversal](/solution/0100-0199/0145.Binary%20Tree%20Postorder%20Traversal/README_EN.md)
+- [Binary Tree Inorder Traversal](/solution/0000-0099/0094.Binary%20Tree%20Inorder%20Traversal/README_EN.md)
 - [Symmetric Tree](/solution/0100-0199/0101.Symmetric%20Tree/README_EN.md)
 - [Invert Binary Tree](/solution/0200-0299/0226.Invert%20Binary%20Tree/README_EN.md)
 - [Binary Tree Level Order Traversal](/solution/0100-0199/0102.Binary%20Tree%20Level%20Order%20Traversal/README_EN.md)

solution/0000-0099/0094.Binary Tree Inorder Traversal/README.md

@@ -24,14 +24,23 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
-递归遍历。
+递归遍历或利用栈实现非递归遍历。
+
+非递归的思路如下：
+
+1. 定义一个栈
+2. 将树的左节点依次入栈
+3. 左节点为空时，弹出栈顶元素并处理
+4. 重复 2-3 的操作
 
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
+递归：
+
 ```python
 # Definition for a binary tree node.
 # class TreeNode:
@@ -51,10 +60,36 @@ class Solution:
         return res
 ```
 
+非递归：
+
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def inorderTraversal(self, root: TreeNode) -> List[int]:
+        s = []
+        res = []
+        while root or s:
+            if root:
+                s.append(root)
+                root = root.left
+            else:
+                root = s.pop()
+                res.append(root.val)
+                root = root.right
+        return res
+```
+
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
+递归：
+
 ```java
 /**
  * Definition for a binary tree node.
@@ -91,6 +126,46 @@ class Solution {
 }
 ```
 
+非递归：
+
+```java
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public List<Integer> inorderTraversal(TreeNode root) {
+        if (root == null) {
+            return Collections.emptyList();
+        }
+        List<Integer> res = new ArrayList<>();
+        Deque<TreeNode> s = new ArrayDeque<>();
+        while (root != null || !s.isEmpty()) {
+            if (root != null) {
+                s.push(root);
+                root = root.left;
+            } else {
+                root = s.pop();
+                res.add(root.val);
+                root = root.right;
+            }
+        }
+        return res;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0094.Binary Tree Inorder Traversal/README_EN.md

@@ -34,6 +34,8 @@
 
 ### **Python3**
 
+Recusive:
+
 ```python
 # Definition for a binary tree node.
 # class TreeNode:
@@ -53,8 +55,34 @@ class Solution:
         return res
 ```
 
+Non-recursive:
+
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def inorderTraversal(self, root: TreeNode) -> List[int]:
+        s = []
+        res = []
+        while root or s:
+            if root:
+                s.append(root)
+                root = root.left
+            else:
+                root = s.pop()
+                res.append(root.val)
+                root = root.right
+        return res
+```
+
 ### **Java**
 
+Recursive:
+
 ```java
 /**
  * Definition for a binary tree node.
@@ -91,6 +119,46 @@ class Solution {
 }
 ```
 
+Non-recursive:
+
+```java
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public List<Integer> inorderTraversal(TreeNode root) {
+        if (root == null) {
+            return Collections.emptyList();
+        }
+        List<Integer> res = new ArrayList<>();
+        Deque<TreeNode> s = new ArrayDeque<>();
+        while (root != null || !s.isEmpty()) {
+            if (root != null) {
+                s.push(root);
+                root = root.left;
+            } else {
+                root = s.pop();
+                res.add(root.val);
+                root = root.right;
+            }
+        }
+        return res;
+    }
+}
+```
+
 ### **...**
 
 ```