This week we will solve the problem "回文子串的数量". Solution is here.

28

This week we will solve the problem "The Next Moment". Solution is here.

32

This week we will solve the problem "为了Hiho的荣耀". Solution is here.

19

This week we will solve the problem "子树中的最小权值". Solution is here.

25

This week we will solve the problem "两个机器人". Solution is here.

37

This week we will solve the problem "元素魔法". Solution is here.

26

This week we will solve the problem "小Hi与矩阵". Solution is here.

36

This week we will solve the problem "小Hi与花盆". Solution is here.

32

This week we will solve the problem "小Hi与钢铁侠". Solution is here.

26

This week we will solve the problem "小Hi与法阵". Solution is here.

39

This week we will solve the problem "无限巧克力谜题". Solution is here.

15

This week we will solve the problem "不一定合法括号序列". Solution is here.

23

This week we will solve the problem "偶树的切分".

33

This week we will solve the problem "皇室成员的名字".

28

This week we will solve the problem "大富翁". Solution is here.

33

This week we will solve the problem "同步H公司的终端". Solution is here.

37

This week we will solve the problem "影院座位". Solution is here.

29

This week we will solve the problem "小Hi的钟表". Solution is here.

36

This week we will solve the problem "观光旅行". Solution is here.

28

This week we will solve the problem "H国的身份证号码II". Solution is here.

28

This week we will solve the problem "合并子目录". Solution is here.

33

This week we will solve the problem "H国的身份证号码I". Solution is here.

34

This week we will solve the problem "区间统计". Solution is here.

41

This week we will solve the problem "缺失的拼图". Solution is here.

52

This week we will solve the problem "统计子目录". Solution is here.

30

This week we will solve the problem "顺序三元组". Solution is here.

71

This week we will solve the problem "或运算和". Solution is here.

49

This week we will solve the problem "召唤佣兽". Solution is here.

37

This week we will solve the problem "迷宫探索". Solution is here.

65

This week we will solve the problem "集合计数". Solution is here.

48

This week we will solve the problem "小Hi和小Ho的对弈游戏". Solution is here.

60

This week we will solve the problem "充电时刻表". Solution is here.

36

This week we will solve the problem "SCI表示法". Solution is here.

43

This week we will solve the problem "无根树变有根树". Solution is here.

37

This week we will solve the problem "相交的铁路线". Solution is here.

21

This week we will solve the problem "自信心". Solution is here.

32

This week we will solve the problem "数组重排3". Solution is here.

46

This week we will solve the problem "大礼堂地毯". Solution is here.

35

This week we will solve the problem "Unimodal Permutation". Solution is here.

46

This week we will solve the problem "Selling Antique Coins". Solution is here.

42

This week we will solve the problem "MSFT". Solution is here.

81

This week we will solve the problem "Array Partition". Solution is here.

78

This week we will solve the problem "道路修建". Solution is here.

51

This week we will solve the problem "最美和弦". Solution is here.

68

This week we will solve the problem "德国心脏病". Solution is here.

64

This week we will solve the problem "分数取模". Solution is here.

46

This week we will solve the problem "逃离迷宫3". Solution is here.

46

This week we will solve the problem "逆序对". Solution is here.

49

This week we will solve the problem "数组重排2". Solution is here.

40

This week we will solve the problem "F1-Score". Solution is here.

51

This week we will solve the problem "矩阵游戏". Solution is here.

42

This week we will solve the problem "古老数字". Solution is here.

61

This week we will solve the problem "逃离迷宫II". Solution is here.

79

This week we will solve the problem "最大集合". Solution is here.

68

This week we will solve the problem "模拟降水". Solution is here.

52

This week we will solve the problem "过河问题".

78

This week we will solve the problem "分数调查". Solution is here。

66

This week we will solve the problem "偶像的条件". Solution is here。

71

This week we will solve the problem "剑刃风暴". Solution is here。

62

This week we will solve the problem "可疑的记录". Solution is here。

88

This week we will solve the problem "投掷硬币". Solution is here。

100

This week we will solve the problem "小Hi和小Ho的礼物". Solution is here。

107

This week we will solve the problem "骑士游历". Solution is here。

49

This week we will solve the problem "一人麻将". Solution is here。

52

This week we will solve the problem "最大子矩阵". Solution is here。

68

This week we will solve the problem "风格不统一如何写程序".

95

This week we will solve the problem "EL SUENO". Solution is here。

62

This week we will solve the problem "A Box of Coins". Solution is here。

79

This week we will solve the problem "Diligent Robots". Solution is here。

91

This week we will solve the problem "Queen Attack".

127

This week we will solve the problem "寻找最大值". Solution is here。

81

This week we will solve the problem 矩形分割". Solution is here。

61

This week we will solve the problem "一面砖墙". Solution is here。

94

This week we will solve the problem "歌德巴赫猜想". Solution is here。

96

This week we will solve the problem "Parentheses Sequence". Solution is here。

82

This week we will solve the problem "Monster Killing". Solution is here。

104

This week we will solve the problem "Tree Restoration". Solution is here。

125

This week we will solve the problem "Legendary Items". Solution is here。

135

This week we will solve the problem "排队接水". Solution is here。

141

This week we will solve the problem "岛屿3". Solution is here。

153

This week we will solve the problem "物品价值". Solution is here。

122

This week we will solve the problem "hiho字符串". Solution is here。

135

This week we will solve the problem "手势识别". Solution is here。

88

This week we will solve the problem "区间价值".

117

This week we will solve the problem "出勤记录II".

61

This week we will solve the problem "出勤记录I". Solution is here。

101

This week we will solve the problem "矩阵填数". Solution is here。

93

This week we will solve the problem "三等分". Solution is here。

104

This week we will solve the problem "水陆距离". Solution is here。

103

This week we will solve the problem "闰秒".

86

This week we will solve the problem "矩形计数". Solution is here。

94

This week we will solve the problem "数组分拆". Solution is here。

96

This week we will solve the problem "拆字游戏". Solution is here。

110

This week we will solve the problem "小Ho的强迫症". Solution is here。

115

This week we will solve the problem "Smallest Substring". Solution is here。

151

This week we will solve the problem "Same Letters In A Row". Solution is here。

105

This week we will solve the problem "Parentheses Matching".

231

This week we will solve the problem "Longest Subsequence". Solution is here。

116

This week we will solve the problem "Ctrl-C Ctrl-V". Solution is here。

135

This week we will solve the problem "Inside Triangle". Solution is here。

140

This week we will solve the problem "Split Array". Solution is here。

153

This week we will solve the problem "Interval Coverage". Solution is here。

148

This week we will solve the problem "Big Plus". Solution is here。

151

This week we will solve the problem "Push Button II". Solution is here。

165

This week we will solve the problem "Push Button I". Solution is here。

659

This week we will solve the problem "Smallest Rectangle". Solution is here。

164

This week we will solve the problem "Keywords Filter". Solution is here。

159

This week we will solve the problem "Logic Expression Tree". Solution is here。

160

This week we will solve the problem "Gas Stations". Solution is here。

197

This week we will solve the problem "Circle Detect". Solution is here。

185

This week we will solve the problem "Sorting Photo Files". Solution is here。

178

This week we will solve the problem "Boarding Passes". Solution is here。

178

This week we will solve the problem "Target Sum". Solution is here。

168

This week we will solve the problem "Total Hamming Distance". Solution is here。

209

This week we will solve the problem "Inventory is Full". Solution is here。

154

This week we will solve the problem "Powers of Two". Solution is here。

113

This week we will solve the problem "Smallest Sub Array". Solution is here。

101

This week we will solve the problem "The Lastest Time". Solution is here。

91

This week we will solve the problem "Guess Number with Lower or Higher Hints". Solution is here。

121

This week we will solve the problem "Building Heap". Solution is here。

179

This week we will solve the problem "Five in a Row".

153

This week we will solve the problem "MS Recognition". Solution is here。

117

This week we will solve the problem "Registration Day". Solution is here。

109

This week we will solve the problem "Composition". Solution is here。

146

This week we will solve the problem "Shortening Sequence". Solution is here。

144

This week we will solve the problem "积水的城市2". Solution is here。

115

This week we will solve the problem "等式填空". Solution is here。

172

This week we will solve the problem "逆序单词". Solution is here。

221

This week we will solve the problem "图片排版". Solution is here。

153

This week we will solve the problem "奖券兑换". Solution is here。

264

This week we will solve the problem "图像算子". Solution is here。

187

This week we will solve the problem "修补木桶". Solution is here。

256

This week we will solve the problem "Playfair密码表".

273

This week we will solve the problem "凸多边形". Solution is here。

121

This week we will solve the problem "震荡数组". Solution is here。

97

This week we will solve the problem "小P的强力值". Solution is here。

100

This week we will solve the problem "小Ho的防护盾". Solution is here。

105

This week we will solve the problem "分隔相同整数". Solution is here。

129

This week we will solve the problem "罚抄一百遍". Solution is here。

166

This week we will solve the problem "积水的城市". Solution is here。

167

This week we will solve the problem "满减优惠".

252

This week we will solve the problem "Counting Islands II". Solution is here。

162

This week we will solve the problem "Popular Products". Solution is here。

171

This week we will solve the problem "Binary Watch". Solution is here。

243

This week we will solve the problem "Nature Numbers". Solution is here。

184

This week we will solve the problem "Part-Time Jobs". Solution is here。

219

This week we will solve the problem "Stable Members".

294

This week we will solve the problem "Full Binary Tree Picture".

499

This week we will solve the problem "Constraint Checker". Solution is here.

281

This week we will solve the problem "Robots Crossing River". Solution is here.

245

This week we will solve the problem "Dice Possibility". Solution is here.

302

This week we will solve the problem "A Game". Solution is here.

314

This week we will solve the problem "Matrix Sum". Solution is here.

329

This week we will solve the problem "Email Merge". Solution is here.

443

This week we will solve the problem "Word Construction". Solution is here.

224

This week we will solve the problem "Basic Arithmetic Calculator.

408

This week we will solve the problem "Biinary Numbers". Solution is here.

818

This week we will solve the problem "Array Rearrangement". Solution is here.

334

This week we will solve the problem "Maze Escape". Solution is here.

289

This week we will solve the problem "Separating Same Characters". Solution is here.

334

This week we will solve the problem "Ordered Binary String". Solution is here.

394

This week we will solve the problem "Hilbert Curve". Solution is here.

309

This week we will solve the problem "Making Palindrome". Solution is here.

319

This week we will solve the problem " Tree or Not". Solution is here.

317

This week we will solve the problem " String Folding". Solution is here.

304

This week we will solve the problem " Region Perimeter". Solution is here.

533

This week we will solve the problem "Invalid Binary Numbers". Solution is here.

330

This week we will solve the problem "Binary Fractions". Solution is here.

182

This week we will solve the problem "Counting Islands". Solution is here.

264

This week we will solve the problem "Task Distribution".

382

This week we will solve the problem "Crossing Restricted Zone". Solution is here.

224

This week we will solve the problem "Stock Prices". Solution is here.

259

This week we will solve the problem "Difference of Interval Collections". Solution is here.

252

This week we will solve the problem "Building in Sandbox". Solution is here.

262

This week we will solve the problem "Demo Day". Solution is here.

305

This week we will solve the problem "403 Forbidden". Solution is here.

261

This week we will solve the problem "Font Size".

382

This week let's learn using bitset.

514

This week we will solve the problem "子矩阵求和". Solution is here.

548

This week we will solve the problem "智力竞赛". Solution is here.

748

This week we will solve the problem "机会渺茫".

1096

This week we will solve the problem "hiho密码".

1650

This week we will solve the problem "扫地机器人". Here is the solution.

332

This week we will solve the problem "自行车架". Here is the solution.

363

This week we will solve the problem "清理海报". Here is the solution.

351

This week we will solve the problem "买零食".

518

This week we will solve the problem "舰队游戏". Here is the solution.

249

This week we will solve the problem "建造基地". Here is the solution.

293

This week we will solve the problem "优化延迟". Here is the solution.

181

This week we will solve the problem "九宫".

178

This week let's learn the 2SAT problem.

117

This week let's learn the 2SAT problem.

119

This week let's learn Suffix Automaton.

113

This week let's learn Suffix Automaton.

147

This week let's learn Suffix Automaton.

182

This week let's learn Suffix Automaton.

225

This week let's learn Suffix Automaton.

146

This week let's learn Suffix Automaton.

196

This week let's learn how to use GeoHash to find near POIs.

173

This week let's learn GeoHash's encoding and decoding with Little Hi and Little Ho.

153

This week let's learn QuadTree with Little Hi and Little Ho.

159

This week let's keep learning suffix array with Little Hi and Little Ho.

149

This week let's keep learning suffix array with Little Hi and Little Ho.

278

This week let's keep learning suffix array with Little Hi and Little Ho.

323

This week let's learn suffix array with Little Hi and Little Ho.

410

This week let's solve the maximum weight closure problem.

2176

This week let's solve the problem of minimum path cover in DAG using max flow algorithm.

1068

This week let's solve a problem using max flow algorithm.

659

This week let's learn max-flow min-cut theory.

819

This week let's learn Ford-Fulkerson, an algorithm to solve maximum flow problem.

333

This week we will learn how to solve problem "Image Encryption".Here is the solution.

295

This week we will learn how to solve problem "Fibonacci".Here is the solution.

356

This week we will learn how to solve problem "Total Highway Distance".Here is the solution.

443

This week we will learn how to solve problem "Farthest Point".Here is the solution.

456

This week we will learn how to solve problem "Increase Charisma Points".Here is the solution.

465

This week we will learn how to solve problem "Tower Defense Game".Here is the solution.

438

This week we will learn how to solve problem "Memory Allocating Algorithm".Here is the solution.

295

This week we will learn how to solve problem "Give My Text Back".Here is the solution.

535

This week learn Size Balanced Tree, a kind of balanced search tree with amortized time O(logn) for each operation.

424

This week solve a problem using Splay Tree.

189

This week learn Splay Tree, a kind of balanced search tree with amortized time O(logn) for each operation.

220

This week learn Treap, a kind of balanced search tree whose expected depth is O(logn).

252

This week solve the sudoku problem with Little Hi and Little Ho, using dancing links.

235

Learn dancing links with Little Hi and Little Ho, the technique suggested by Donald Knuth to efficiently implement some search algorithms.

397

This week Little Hi and Little Ho try to solve the famous 8-puzzle problem with the famous A* algorithm.

432

This week Little Hi and Little Ho try to solve a chess knights meeting problem.

253

This week Little Hi and Little Ho try to solve an arithmetical card game -- 24 points.

433

Learn how to solve linear congruence equations with Little Hi and Little Ho.

296

Learn Euler's totient function or Euler's phi function with Little Hi and Little Ho.

673

Learn Extended Euclidean algorithm with Little Hi and Little Ho.

477

Solve the Josephus problem with Little Hi and Little Ho.

787

Prime or not prime： that is the question.

755

Prime or not prime： that is the question.

3918

This week we will solve the problem "Events Arrangement". Here is the solution.

931

This week we will solve the problem "Swimming Plans". Here is the solution.

743

This week we will solve the problem "Divisors". Here is the solution.

860

This week we will solve the problem "Coordinates". Here is the solution.

577

This week we will solve the problem "S-expression". Here is the solution.

392

This week we will solve the problem "Spring Outing". Here is the solution.

360

This week we will solve the problem "Numeric Keypad". Here is the solution.

236

This week we will solve the problem "Lucky Substrings". Here is the solution.

186

This week we will solve the problem "Recruitment". Here is the solution.

67

This week we will solve the problem "Islands Travel". Here is the solution.

100

This week we will solve the problem "Professor Q's Software". Here is the solution.

133

This week we will solve the problem "Magic Box". Here is the solution.

173

This week we will solve the problem "Troublesome Power Supply". Here is the solution.

158

This week we will solve the problem "Shortest Proper Prefix". Here is the solution.

288

This week we will solve the problem "Koch Snowflake". Here is the solution.

382

This week we will solve the problem "Suzhou Adventure". Here is the solution.

183

This week we will solve the problem "Colorful Lecture Note". Here is the solution.

175

This week we will solve the problem "Individual Income Tax". Here is the solution.

174

This week we will solve the problem "Arithmetic Puzzles". Here is the solution.

171

This week we will solve the problem "Disk Storage". Here is the solution.

370

This week we will solve the problem "Constellations". Here is the solution.

210

This week we will solve the problem "Divided Product". Here is the solution.

371

This week we will solve the problem "HIHO Drinking Game". Here is the solution.

406

This week we will solve the problem "Lost in the City". Here is the solution.

264

This week we will solve the problem "Clicker". Here is the solution.

406

This week we will solve the problem "Have Lunch Together". Here is the solution.

488

This week we will solve the problem "Highway". Here is the solution.

3721

This week we will solve the problem "Right-click Context Menu". Here is the solution.

874

This week we will solve the problem "Hamiltonian Cycle". Here is the solution.

1488

This week we will solve the problem "Browser Caching". Here is the solution.

714

This week we will solve the problem "Combination Lock". Here is the solution.

473

This week we will solve the problem "String Matching Content Length". Here is the solution.

587

This week we will solve the problem "Performance Log". Here is the solution.

345

This week we will solve the problem "Beautiful String". Here is the solution.

384

There is an awards event in convenience store.

308

Little Hi and Little Ho heard a nearby convenience store is offering a discount.

489

School campus network seemed to have a problem again.

378

Summer vacation is coming

493

After suffering from computer virus, Little Hi and Little Ho's school is rebuilding the campus network.

396

After suffering from computer virus, Little Hi and Little Ho's school is rebuilding the campus network.

214

Little Hi and Little Ho will face the last puzzle.

269

After having collected all items, little Hi and little Ho have to face to a new problem.

436

It's weekend, little Hi and little Ho are having fun in the dorm.

509

Hack? Hack!

456

Little Hi and Little Ho is back! Let's take a look, what happened to them today?

466

The third game of Alice and Bob.

418

Alice and Bob will play with coins this week.

565

Today we will meet Alice and Bob, they will give us a new series.

930

Let's continue dominoes game problem.

830

Let's continue dominoes game problem.

2984

This week, we still learn a new divide and conquer algorithm.

3476

The 5th week of learning divide and conquer algorithm. Let's study a new divide and conquer algorithm.

1627

The 4th week of learning divide and conquer algorithm. Let's see a classic problem.

2159

This week let's study a very useful application of binary search, reducing optimization problems to decision problems.

420

The weekly problem is also about divide and conquer algorithms.

317

After having studied bipartite graph, we will start a new series about divide and conquer algorithms.

242

Chinese New Year is about to end, Nettle's aunt ask him for last help.

195

Happy Chinese New Year, Let's continue to arrange blind date.

146

The adventure of Little Hi and Little Ho will continue after the Spring Festival. Now let's enjoy the holidays.

140

"Little Hi!!! Where's the perfect solution you promised?!!! What do you mean GUESS in this last step!" little Ho says, with rage filled up his mind.

133

"Zero ... zero each time! It would be so convenient if they all reverse in one move as in computer!" little says, wite anger on his face.

313

"If ... I died after this step, little Hi, please take care of my parents ..." little Ho says, with tears in his eyes.

387

These is no love without reason, and there is no reduction of time comlexity without reason!

458

Keep looking for the bigest candy ... will make you fatter!

703

The minimum of all is the minimum of part!

637

A choice to solve huge(?) scale problem : reduce the scale by one

680

Algorithms... well, some of them, is just simply traversal and ... some improvement!

726

Well, right! Ten times of an algorithm with time comlexity of O(N^2) is good enough to take over the algorithm with time comlexity of O(N^3)! But, what if I tell you this algorithm is only writen in 5 lines?

807

Straightest is the shortest! But ... only in 2-dimensional graph?

537

To practice than to read ! And then ... practice more !

196

This world is no longer continuous in my eyes! Ho says so.

248

Segment-tree seems to be too much for RMQ problem ? Let's see some more powerful usage!

214

Less is more, far is near - will ST algorithm reborn after calculate less intervals?

317

SImple modification make easy problem really complicated ! What's the secrets that behind the RMQ problem ?!

468

It is so embarrassing that Hi and Ho applied an advanced LCA algorithm but nothing goes better. How will Hi and Ho deal with this?

394

Select dyslexia！How will Hi and Ho do ?

1371

In order to cover the uesless of algorithm, should we spent thounds to buy servers? No! Ho says so.

1653

Ally? Or Enemy? To be, or not to be? How can a computer solve this ?

423

"We came from the same ancient!", people having same last name will say so. But which ancient is the nearest one? Hi and Ho will let you know!

460

The painting on Ho's toy tree has been erased due to Ho's endless rub! What will Ho do ?

337

"Diameter of tree", such a classic problem must be collected in our sets of tree problems that represents "Recursion"! Wanna know how to solve it?

433

Calculating binary tree post-order traversal from given pre-order and in-order traversal is just shown up in the online test of Alibaba!~ Just come and see how Hi and Ho solve it!

639

"State Compression" is useful tool to deal with many circumstances. Let's see how Hi and Ho put their cakes!

362

Sometimes the division of state will be uncertain, and in this case, the state compression will help a lot!

541

In another parallel universe, the story of Hi and Ho has been changed magically! What's variants of "knapsack" problem? Can we eat it? Does it tasty? And how can we eat it?

913

The "0/1 knapsack" problem is not only a simply dynamic programming model! Let's see how Ho use it to solve his problem~

538

You should already know the problem "Triangle of numbers", but as the Confucius says "Reviewing leads to new". So why not come and see how Hi and Ho solve it?

445

Do you still remember the problem that Mr.Hexie presented in Hiho! Week 3? This time Hi and Ho will end it !

617

Pattern Matching is an everlasting topic in String Processing, and KMP algorithm is the brightest one with no doubt! So come and learn it with Hi and Ho~

669

String autocompletion is important both in input method and search engine, but do you know how to implemtent it?

1624

You must be familiar with such a classic problem as "The longest palindrome"? But do you know the 3 kinds of way to solve it? Just have a try!

1162

Test

2