solves leetcode #99 recover bst in java

Author: anishLearnsToCode

Diff for: README.md

@@ -91,7 +91,7 @@
 |  96  | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees)                                                                    |                                                             [![Java](assets/java.png)](src/UniqueBinarySearchTrees.java)                                                             |                                                                                                                                   |
 |  97  | [Interleaving String](https://leetcode.com/problems/interleaving-string)                                                                                  |                                                               [![Java](assets/java.png)](src/InterleavingString.java)                                                                |                                                                                                                                   |
 |  98  | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree)                                                                  |                                                            [![Java](assets/java.png)](src/ValidateBinarySearchTree.java)                                                             |                                                                                                                                   |
-|  99  | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree)                                                                    |                                                                                                                                                                                      |                                                                                                                                   |
+|  99  | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree)                                                                    |                                                             [![Java](assets/java.png)](src/RecoverBinarySearchTree.java)                                                             |                                                                                                                                   |
 | 100  | [Same Tree](https://leetcode.com/problems/same-tree)                                                                                                      |                                          [![Java](assets/java.png)](src/SameTree.java) [![Python](assets/python.png)](python/same_tree.py)                                           |                                                                                                                                   |
 | 101  | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree)                                                                                            |                                     [![Java](assets/java.png)](src/SymmetricTree.java) [![Python](assets/python.png)](python/symmetric_tree.py)                                      |                                                                                                                                   |
 | 102  | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal)                                                      |                                                          [![Java](assets/java.png)](src/BinaryTreeLevelOrderTraversal.java)                                                          |                                                                                                                                   |

Diff for: src/RecoverBinarySearchTree.java

@@ -0,0 +1,33 @@
+// https://leetcode.com/problems/recover-binary-search-tree
+// T: O(n)
+// S: O(log(n))
+
+public class RecoverBinarySearchTree {
+    TreeNode first, second, previous = new TreeNode(Integer.MIN_VALUE);
+
+    public void recoverTree(TreeNode root) {
+        inorder(root);
+        swapValues(first, second);
+    }
+
+    private void inorder(TreeNode root) {
+        if (root == null) return;
+        inorder(root.left);
+
+        if (first == null && root.val < previous.val) {
+            first = previous;
+        }
+        if (first != null && root.val < previous.val) {
+            second = root;
+        }
+        previous = root;
+
+        inorder(root.right);
+    }
+
+    private void swapValues(TreeNode a, TreeNode b) {
+        int temp = a.val;
+        a.val = b.val;
+        b.val = temp;
+    }
+}