Update README.md

Author: TonyStark-19

README.md

@@ -157,6 +157,7 @@ Implementation of Tree and **solutions to various LeetCode problems with differe
 
 - [ ] **Binary tree** - building binary tree and implementing different tree traversals.
 - [ ] **Bottom view of binary tree** - to find the tree nodes which are visible from bottom
+- [ ] **Build tree** - leetcode 105
 - [ ] **Count nodes** - to count number of nodes in a tree
 - [ ] **Diameter of Binary Tree** - leetcode 543
 - [ ] **Diameter of Binary Tree 2** - leetcode 543 (more optimal)