Two-Hundred-Fifty-Nine Commit: Add Invert Binary Tree problem to Concurrency section

Author: AAdewunmi

src/Concurrency/Problem_2_Invert_Binary_Tree.java

@@ -0,0 +1,29 @@
+package Concurrency;
+
+// Problem Statement: Invert Binary Tree (medium)
+// LeetCode Question: 226. Invert Binary Tree
+
+public class Problem_2_Invert_Binary_Tree {
+
+    class TreeNode {
+        int val;
+        TreeNode left;
+        TreeNode right;
+        public TreeNode(int val) {
+            this.val = val;
+            this.left = null;
+            this.right = null;
+        }
+    }
+
+    public static TreeNode invertTree(TreeNode root) {
+        if (root != null) {
+            invertTree(root.left);
+            invertTree(root.right);
+            TreeNode temp = root.right;
+            root.right = root.left;
+            root.left = temp;
+        }
+        return root;
+    }
+}