Materials

2025/26
2024/25
2023/24
2022/23
2021/22
2025/26 C++ Foundation Course
28 Jan - 20 Mar 2026
Our OI Journey
Preface
Programming Environment
Chapter 0
Hello, World!
Chapter 1
Basic Data Types
Chapter 2
Branching
Chapter 3
Loops
Chapter 4
Time Complexity
Chapter 5
Arrays
Chapter 6
Data Structures I
Chapter 7
String
Chapter 8
Functions
Chapter 9
Partial Sum
Chapter 10
Structures
Ext. Chapter 11
Sorting
Ext. Chapter 12
Data Structures II
Ext. Chapter 13
Prime Numbers
Ext. Chapter 14
Extra Training
HKOI 2025/26 Final Event Briefing Session
5 Dec 2025
NOIP 2025 Briefing Session
28 Nov 2025
HKOI 2025/26 Heat Event Briefing Session
5 Nov 2025
SDIC 2025 Final Event Briefing Session
31 Oct 2025
SDIC 2025 Heat Event Briefing Session
19 Sep 2025
2025/26 Team Qualification Test
8, 9 Jul 2026
Paper 1
Question Paper
Paper 2
Question Paper
Answer SheetSuggested Answers
2025/26 HKOI Heat Mock
5 Nov 2025
Paper 1
Question Paper
Paper 2
Question Paper
Answer SheetSuggested Answers
2025/26 Team Nomination Test
15 Oct 2025
RulesPaper 1
Question Paper
Paper 2
Question Paper
Answer SheetSuggested Answers
2025/26 Team Placement Test
27 Jun 2025
Paper 1
Question Paper
Paper 2
Question Paper
Answer Sheet
2024/25 C++ Foundation Course
27 Feb - 19 Mar 2025
Our OI Journey
Preface
Programming Environment
Chapter 0
Hello, World!
Chapter 1
Basic Data Types
Chapter 2
Branching
Chapter 3
Loops
Chapter 4
Arrays
Chapter 5
Data Structures I
Chapter 6
Pair
Chapter 7
Sorting
Chapter 8
Data Structures II
Chapter 9
String
Chapter 10
Time Complexity
Ext. Chapter 11
Functions
Ext. Chapter 12
Structures
Ext. Chapter 13
Partial Sum
Ext. Chapter 14
2024/25 HKOI Heat Mock
6 Nov 2024
Paper 1
Question Paper
Paper 2
Question Paper
Answer SheetSuggested Answers
Extra Training
Plan 2025
7 May 2025
HKOI 2024/25 Final Event Briefing Session
6 Dec 2024
NOIP 2024 Briefing Session
29 Nov 2024
HKOI 2024/25 Heat Event Briefing Session
8 Nov 2024
SDIC 2024 Final Event Briefing Session
25 Oct 2024
SDIC 2024 Heat Event Briefing Session
19 Sep 2024
Into a New Era of HKOI
2 Oct 2024
Past Questions
Basic Data Types
Control Structures
Code Tracing
2023/24 C++ Foundation Course
30 Jan - 18 Apr 2024
History of TWGSS OI
Preface
Course Outline
Introduction
Programming Environment
Chapter 0
Hello, World!
Chapter 1
Basic Data Types
Chapter 2
Branching
Chapter 3
Loops
Chapter 4
Time Complexity
Chapter 5
Arrays
Chapter 6
Data Structures
Chapter 7
Structures
Chapter 8
Functions
Chapter 9
Sorting
Chapter 10
Prime Numbers
Chapter 11
Partial Sum
Chapter 12
2023/24 HKOI Heat Mock
9 Nov 2023
Question PaperAnswer SheetSuggested Answers
Extra Material
HKOI 2023/24 Heat Event Preparation
2022/23 C++ Foundation Course
28 Feb - 13 Mar 2023
Preface
28 Feb 2023
Lesson 1
28 Feb 2023
Lesson 2
1 Mar 2023
Lesson 3
6 Mar 2023
Lesson 4
7 Mar 2023
Lesson 5
8 Mar 2023
Lesson 6
13 Mar 2023
2022/23 C++ Crash Course
19 Sep - 7 Oct 2022
Lesson 1
19 Sep 2022
Lesson 2
21 Sep 2022
Lesson 3
23 Sep 2022
Lesson 4
26 Sep 2022
Lesson 5
28 Sep 2022
2022/23 HKOI Heat Mock
11 Nov 2022
Question Paper
Extra Training
HKOI 2022/23 Heat Event Preparation
9 Nov 2022
2022 C++ Coding Workshop
21 Mar - 18 Apr 2022
Lesson 1
21 Mar 2022
Lesson 2
24 Mar 2022
Lesson 3
28 Mar 2022
Lesson 4
31 Mar 2022
Lesson 5
4 Apr 2022
Lesson 6
7 Apr 2022
Lesson 7
11 Apr 2022
Lesson 8
14 Apr 2022
Extra Training
HKSC 2022 Briefing Session
22 Jul 2022