这个题，不要忘了一开始check num == 1?

  Given a sorted linked list, delete all duplicates such that each element appear only once. Example…

The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ... 1&nbs…

18. 4Sum -Medium descrition Given an array S of n integers, are there elements a, b, c, and d in S such that a…

Medium Given n nodes labeled from “0 to n - 1 and a list of undirected edges (each edge is a pair of nod…

/* 89. Gray Code Total Accepted: 57721 Total Submissions: 160293 Difficulty: Medium The gray code is a binary …

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you…

题目 给定一个数组和一个值，在原地删除与值相同的数字，返回新数组的长度。 元素的顺序可以改变，并且对新的数组不会有影响。 样例 给出一个数组[0,4,4,0,0,2,4,4]，和值 4返回 4 并且4个元素的新数组为[0…

emmm…动态规划就练几个简单的题吧，其他的搞不定，告辞告辞~ 如何想到使用DP 找最大值/最小值(maximum/minimum) 判断是否可行(yes/no) 所有可能结果的数量(count) 解题思路 …

Medium 过两天面Yelp, k sum在最近面经里频率还行，拿来做做吧。还是处理edge case的时候卡了一下, 记一下内部的while循环要记得加上bound: left < right, 顺便再记一下这…

题目 Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmi…

题目描述 Given a collection of integers that might contain duplicates, nums, return all possible subsets. Note: El…