摘要：
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, e 阅读全文
摘要：
Given a list of unique words. Find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e. words[i] + 阅读全文
摘要：
Implement a trie with insert, search, and startsWith methods. Note: You may assume that all inputs are consist of lowercase letters a-z. Solution: 阅读全文