摘要： Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. 阅读全文

摘要： The gray code is a binary numeral system where two successive values differ in only one bit. Given a non-negative integer n representing the total num 阅读全文

摘要： Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representati 阅读全文