排序map、pq、stack。固定 递归 贪心 开关 二分 滑动窗口（固递贪开二滑）

摘要： ［抄题］： Given a nested list of integers, implement an iterator to flatten it. Each element is either an integer, or a list -- whose elements may also be 阅读全文

摘要： ［抄题］： Given a string, your task is to count how many palindromic substrings in this string. The substrings with different start indexes or end indexes 阅读全文