题目： You are given two linked lists representing two non-negative numbers. The digits are stored in reverse ord…

题目描述 Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, …)…

Group Anagrams 最新更新请见：https://yanjia.me/zh/2019/01/… Given an array of strings, group anagrams together.…

Valid Roman Numeral 正则表达式 思路 首先我们要熟悉罗马数的表达方式。M是1000，D是500，C是100，L是50，X是10，V是5，I是1。验证字符串是否是罗马数，我们先看一下有效的罗马数是什么样…

Climbing Stairs You are climbing a stair case. It takes n steps to reach to the top. Each time you can either …

Kth Largest Element in an Array Find the kth largest element in an unsorted array. Note that it is the kth lar…

1. 题目 Implement regular expression matching with support for ‘.’ and ‘*’. ‘.R…

  Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the num…

  Given a singly linked list, return a random node’s value from the linked list. Each node must hav…

  Given an array of integers and an integer k, you need to find the total number of continuous subar…

  We are given an array asteroids of integers representing asteroids in a row. For each asteroi…

题目： Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left…