摘要：
Description:Count the number of prime numbers less than a non-negative number,n.传送门：https://leetcode.com/problems/count-primes/尽可能把查找次数缩小，直接用双重for会超时。... 阅读全文
摘要：
There are a total ofncourses you have to take, labeled from0ton - 1.Some courses may have prerequisites, for example to take course 0 you have to firs... 阅读全文
摘要：
Given a binary tree, return thezigzag level ordertraversal of its nodes' values. (ie, from left to right, then right to left for the next level and al... 阅读全文