北叶青藤

摘要： Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. Th 阅读全文

摘要： Given an array of strings, group anagrams together. For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], Return: 阅读全文

摘要： Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number m 阅读全文

摘要： Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors. OJ's undirected graph serialization: Nodes are labeled 阅读全文

摘要： Design a data structure that supports all following operations in O(1) time. insert(val): Inserts an item val to the set if not already present.remove 阅读全文

摘要： Find the sum of all left leaves in a given binary tree. Example: 阅读全文

摘要： Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), determine if a person could attend all mee 阅读全文

摘要： 一个sequence，里面都是整数，求最长的subsequence的长度，使得这个subsquence的最大值和最小值相差不超过1. 比如[1,3,2,2,5,2,3,7]最长的subsequence是[3,2,2,2,3],所以应该返回5. 分析： 这题可以先排序，然后找出两个相差1的相邻值的最大 阅读全文

摘要： Given a sorted array of integers nums and integer values a, b and c. Apply a function of the form f(x) = ax2 + bx + c to each element x in the array. 阅读全文

摘要： Given a string, sort it in decreasing order based on the frequency of characters. Example 1: Example 2: 阅读全文