solve problem Invert Binary Tree

Author: P-ppc

README.md

@@ -15,4 +15,5 @@ All solutions will be accepted!
 |292|[Nim Game](https://leetcode-cn.com/problems/nim-game/description/)|[java/py/js](./algorithms/NimGame)|Easy|
 |557|[Reverse Words In A String III](https://leetcode-cn.com/problems/reverse-words-in-a-string-iii/description/)|[java/py/js](./algorithms/ReverseWordsInAStringIII)|Easy|
 |104|[Maximum Depth Of Binary Tree](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/description/)|[java/py/js](./algorithms/MaximumDepthOfBinaryTree)|Easy|
-|617|[Merge Two Binary Trees](https://leetcode-cn.com/problems/merge-two-binary-trees/description/)|[java/py/js](./algorithms/MergeTwoBinaryTrees)|Easy|
+|617|[Merge Two Binary Trees](https://leetcode-cn.com/problems/merge-two-binary-trees/description/)|[java/py/js](./algorithms/MergeTwoBinaryTrees)|Easy|
+|226|[Invert Binary Tree](https://leetcode-cn.com/problems/invert-binary-tree/description/)|[java/py/js]|(./algorithms/InvertBinaryTree)|Easy|

algorithms/InvertBinaryTree/README.md

@@ -0,0 +1,2 @@
+# Invert Binary Tree
+We can use resursion to solve this, like [this](./solution.py), or use loop to solve this, like [this](./Solution.java)

algorithms/InvertBinaryTree/Solution.java

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+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public TreeNode invertTree(TreeNode root) {
+        if (root == null) {
+            return null;
+        }
+        List<TreeNode> list = new ArrayList<TreeNode>();
+        list.add(root);
+        while (list.size() > 0) {
+            TreeNode node = list.get(0);
+            list.remove(node);
+            TreeNode tempNode = node.left;
+            node.left = node.right;
+            node.right = tempNode;
+            if (node.left != null) {
+                list.add(node.left);
+            }
+            if (node.right != null) {
+                list.add(node.right);
+            }
+        }
+        return root;
+    }
+}

algorithms/InvertBinaryTree/solution.js

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+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+var invertTree = function(root) {
+    if (root === null) {
+        return null
+    }
+    let tempNode = root.left
+    root.left = root.right
+    root.right = tempNode
+    
+    root.left = invertTree(root.left)
+    root.right = invertTree(root.right)
+    return root
+};

algorithms/InvertBinaryTree/solution.py

@@ -0,0 +1,19 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def invertTree(self, root):
+        """
+        :type root: TreeNode
+        :rtype: TreeNode
+        """
+        if root is None:
+            return None
+        root.left, root.right = root.right, root.left
+        root.left = self.invertTree(root.left)
+        root.right = self.invertTree(root.right)
+        return root