solves consruct string from binary tree

Author: anishLearnsToCode

Diff for: README.md

@@ -160,7 +160,7 @@
 | 599 | [Minimum Index Sum of 2 Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists) | [![Java](assets/java.png)](src/MinimumIndexSumOfTwoLists.java) [![Python](assets/python.png)](python/minimum_index_sum_of_two_lists.py) |
 | 604 | 🔒 [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator) | |
 | 605 | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers) | [![Java](assets/java.png)](src/CanPlaceFlowers.java) [![Python](assets/python.png)](python/can_place_flowers.py) |
-| 606 | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree) | |
+| 606 | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree) | [![Java](assets/java.png)](src/ConstructStringFromBinaryTree.java) [![Python](assets/python.png)](python/construct_string_from_binary_tree.py)|
 | 617 | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees) | |
 | 624 | [Maximum Distance in Arrays](https://leetcode.com/problems/maximum-distance-in-arrays) | |
 | 628 | [Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers) | |

Diff for: python/construct_string_from_binary_tree.py

@@ -0,0 +1,14 @@
+# 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 tree2str(self, root: TreeNode) -> str:
+        if root is None: return ''
+        if root.left is None and root.right is None: return f'{root.val}'
+        if root.right is None: return f'{root.val}({self.tree2str(root.left)})'
+        return f'{root.val}({self.tree2str(root.left)})({self.tree2str(root.right)})'

Diff for: src/ConstructStringFromBinaryTree.java

@@ -0,0 +1,8 @@
+public class ConstructStringFromBinaryTree {
+    public String tree2str(TreeNode root) {
+        if (root == null) return "";
+        if (root.left == null && root.right == null) return root.val + "";
+        return root.val + "(" + tree2str(root.left) + ")"
+                + (root.right == null ? "" : "(" + tree2str(root.right) + ")");
+    }
+}