摘要： There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have t 阅读全文

摘要： Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't 阅读全文

摘要： Implement a trie with insert, search, and startsWith methods. Note:You may assume that all inputs are consist of lowercase letters a-z. 设计一个前缀树，包括inse 阅读全文

摘要： There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have t 阅读全文

摘要： Reverse a singly linked list. 阅读全文

摘要： Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrenc 阅读全文

摘要： Description: Count the number of prime numbers less than a non-negative number, n. 找出小于n的素数个数。 1、用最淳朴的算法果然超时了。 2、埃拉托斯特尼筛法Sieve of Eratosthenes 我们从2开始遍 阅读全文

摘要： Remove all elements from a linked list of integers that have value val. ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 -- 阅读全文

摘要： Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive intege 阅读全文

摘要： Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive. For example, given the range [5, 阅读全文