摘要：
This problem was recently asked by Google. Given a list of numbers and a number k, return whether any two numbers from the list add up to k. For examp 阅读全文
摘要：
Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k num 阅读全文
摘要：
This problem was asked by Google. Implement locking in a binary tree. A binary tree node can be locked or unlocked only if all of its descendants or a 阅读全文