# LeetCode Construct String from Binary Tree

LeetCode Construct String from Binary Tree You need to construct a string consists of parenthesis and integers from a binary tree with the preorder traversing way. The null node needs to be represented by empty parenthesis pair "()". And you need to... Read More

# LeetCode House Robber III

LeetCode House Robber III The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized... Read More

# LeetCode Subtree of Another Tree

LeetCode Subtree of Another Tree Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The... Read More

# LeetCode Binary Tree Tilt

LeetCode Binary Tree Tilt Given a binary tree, return the tilt of the whole tree. The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has... Read More

# LeetCode Minimum Height Trees

LeetCode Minimum Height Trees For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees... Read More

# LeetCode Verify Preorder Serialization of a Binary Tree

LeetCode Verify Preorder Serialization of a Binary Tree One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we record using a sentinel value such as #. ... Read More

# LeetCode Count Complete Tree Nodes

LeetCode Count Complete Tree Nodes Given a complete binary tree, count the number of nodes. Definition of a complete binary tree from Wikipedia: In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the... Read More

# LeetCode Kth Smallest Element in a BST

LeetCode Kth Smallest Element in a BST Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements. Follow up: What if the BST is modified... Read More

# LeetCode Most Frequent Subtree Sum

LeetCode Most Frequent Subtree Sum Given the root of a tree, you are asked to find the most frequent subtree sum. The subtree sum of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node... Read More