Geurney的专栏

Unique SubsetsGiven a list of numbers that may has duplicate numbers, return all possible subsets.ExampleIf S = [1,2,2], a solution is:[ [2], [1], [1,2,2], [2,2], [1,2], []

Find Min in Rotated ArraySuppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).Find the minimum element.You may a

题目汇总：1. strStr A字符串中是否含有B字符串。遍历即可。2. Two Strings Are Anagrams A字符串中的字符是否和B字符串的字符一致（变位词）。数组自动初始化，先加后减。3. Anagrams 找出字符串数组里的变位词。由数组生成字符串key，存入hashmap。3. Compare Strings A字符串中的字符是否包含了B字符串的字符。数组自动

SqrtXImplement int sqrt(int x).Compute and return the square root of x.Examplesqrt(3) = 1sqrt(4) = 2sqrt(5) = 2sqrt(10) = 3ChallengeO(log(x))Solution:

Search 2D matrix IIWrite an efficient algorithm that searches for a value in an m x n matrix, return the occurrence of it.This matrix has the following properties:    * Integers in each

Search Insert PositionGiven a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You may assume

Two Strings Are Anagrams判断两个string里的字符和计数是否一致。Write a method anagram(s,t) to decide if two strings are anagrams or not.ExampleGiven s="abcd", t="dcab", return true.Challeng

Binary SearchFor a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity.If the target number does not exist in the array,

Find Peak ElementThere is an integer array which has the following features:    * The numbers in adjacent positions are different.    * A[0] A[A.length - 1].We define a position P i

Search 2D matrixWrite an efficient algorithm that searches for a value in an m x n matrix.This matrix has the following properties:    * Integers in each row are sorted from left to righ

Rotate StringGiven a string and an offset, rotate string by offset. (rotate from left to right)ExampleGiven "abcdefg"for offset=0, return "abcdefg"for offset=1, return "gabcdef"for

Reverse Words in a String翻转string里的单词顺序。Given an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue is sky the".Solution: public

Longest Words找出数组内最长的stringGiven a dictionary, find all of the longest words in the dictionary.ExampleGiven{ "dog", "google", "facebook", "internationalization", "blabla"}

Binary Search 二分查找。在有序数组中（允许重复数字），查找第一个或最后一个目标数字。时间复杂度为O(logN)。循环方法和递归方法。

3 Sum数组中3个数的和为指定值。Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Example

Median of two Sorted Arrays在两个数组中找到中位数。There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays.ExampleGiven A=[1,2,3,4,5,6] and

Length of Last WordString里最后一个单词的长度Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.If the last word d

Recover Rotated ArrayGiven a rotated sorted array, recover it to sorted array in-place.Example[4, 5, 1, 2, 3] -> [1, 2, 3, 4, 5]ChallengeIn-place, O(1) extra space and O(n) t

Search in Rotated Array IIFollow up for "Search in Rotated Sorted Array":What if duplicates are allowed?Would this affect the run-time complexity? How and why?Write a function to deter

Search in Rotated Sorted ArraySuppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).You are given a target value to

PermutationsGiven a list of numbers, return all possible permutations.ExampleFor nums [1,2,3], the permutaions are: [    [1,2,3],    [1,3,2],    [2,1,3],    [2,3,1],    [3,1,2],

Single NumberGiven 2*n + 1 numbers, every numbers occurs twice except one, find it.ExampleGiven [1,2,2,1,3,4,3], return 4Solution异或： public int singleNumber(int[] A) { i

unique charactersImplement an algorithm to determine if a string has all unique charactersExampleGiven "abc", return trueGiven "aab", return false

Single Numbe IIGiven 3*n + 1 numbers, every numbers occurs triple times except one, find it.ExampleGiven [1,1,2,3,3,3,2,2,4,1] return 4Solution: public int singleNumberII(int[] A)

Single Number IIIGiven 2*n + 2 numbers, every numbers occurs twice except two, find them.ExampleGiven [1,2,2,3,4,4,5,3] return 1 and 5Solution public List singleNumberIII(int[] A) {

Compare StringsCompare two strings A and B, determine whether A contains all of the characters in B.The characters in string A and B are all Upper Caseletters.ExampleFor A = "ABCD", B

Unique PermutationsGiven a list of numbers with duplicate number in it. Find all unique permutations.ExampleFor numbers [1,2,2] the unique permutations are:[    [1,2,2],    [2,1,2], 

Find Min in Rotated Array IISuppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).Find the minimum element.The

Merge Sorted Array IIGiven two sorted integer arrays A and B, merge B into A as one sorted array.NoteYou may assume that A has enough space (size that is greater or equal to m + n) to

Remove duplicates from sorted arrayGiven a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for anot

Remove duplicates from sorted array IIFollow up for "Remove Duplicates":What if duplicates are allowed at most twice?For example,Given sorted array A = [1,1,1,2,2,3],Your function sh

Merge Sorted ArrayMerge two given sorted integer array A and B into a new sorted integer array.ExampleA=[1,2,3,4]B=[2,4,5,6]return [1,2,2,3,4,4,5,6]ChallengeHow can you o

2 sumGiven an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the

strStr (easy)For a given source string and a target string, you should output the "first" index(from 0) of target string in source string.If target is not exist in source, just return -1.

SubsetsGiven a set of distinct integers, return all possible subsets.

First Bad Version Boolean数组中找到第一个true.The code base version is an integer start from 1 to n. One day, someone committed a bad version in the code case, so it caused this version and the follow

Search for a RangeGiven a sorted array of integers, find the starting and ending position of a given target value.If the target is not found in the array, return [-1, -1].ExampleGive

Count and Say按规律生成stringThe count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ...1 is read off as "one 1" or 11. 1个111 is read off