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Competitive Programming and Contests

Teacher: Rossano Venturini
CFU: 6
Period: First semester
Language: English
Classroom: here. Code is d77kira
Lectures schedule: Monday 9-11 Room C1 and Thursday 9-11 Room C1 -- (Google Meet, link on our classroom)
Question time: After lectures or by appointment

Goals and opportunities

The goal of the course is to improve programming and problem-solving skills of the students by facing them with difficult problems and by presenting the techniques that help their reasoning in the implementation of correct and efficient solutions. The importance of these skills has been recognized by the most important software companies worldwide, which evaluate candidates in their job interviews mostly by the ability in addressing such difficult problems (e.g., see here).

A natural goal is to involve the students in the intellectual pleasure of programming and problem solving, also preparing them for the most important international online contests, such as Topcoder, Codeforces, HackerRank, CodeChef, Facebook Hacker Cup, Google Code Jam and so on, for internships in most important companies and their interviews. A desirable side-effect of the course could be to organize and prepare teams of students for online contests.

The course will provide the opportunity of

facing with challenging algorithmic problems;
improving problem solving and programming skills;
getting in touch with some big companies for internships, scholarships, or thesis proposals.

Exam

See these slides. Mandatory exercises for homeworks are in bold.

Extra points for

active participation
serious participation to online contests, e.g., CodeForces, TopCoder, Hacker Rank, Google Code Jam, ...
successful interview with a big company

Implementing solutions for the problems of each lecture is strongly recommended to improve your problem solving skill and to practice with Rust.

I recommend you to create a github repository to collect all your solutions and their descriptions. The repository can be either private or public. In both cases I should be able to access it. Please send me a link to your repository and keep the repository updated. I should be able to monitor your progresses.

Upcoming Exams

Type	Date	Room
Written/Lab	03/02/2022 9:00	Google Meet

Old Exams

Type	Date	Text
Written/Lab	23/01/2018 9:30	Text, TestSet, and Solution
Written/Lab	14/02/2018 9:30	Text, TestSet, and Quadratic solution
Written/Lab	12/06/2018 14:00	Text, TestSet, and Solution
Written/Lab	06/07/2018 9:30	Text and TestSet
Written/Lab	14/01/2019 14:00	Text and TestSet

How to solve a problem

Read carefully the description of the problem.
Make sure you understand the problem by checking the examples.
Design a first trivial solution.
Think about a more efficient solution. The use of some running examples usually helps a lot in finding a better solution. If your are not able to find such solution, try to find some hints by discussing with other students, by asking questions on the group, by looking at the solution in our Web page, or by searching on internet. This is perfectly fine for the first problems and for most difficult ones. In any case, make sure you really understand the solution and the properties it is exploiting!
Write a brief description of your solution in English. Provide an analysis of its time and space complexity.
Implement your own solution.
Submit your implementation to the problem's site. Fix it until it passes all the tests.
Always compare your solution and your implementation with existing ones.

Background

If you wish to refresh your mind on basic Algorithms and Data Structures, I suggest you to look at the well-known book Introduction to Algorithms, 3rd Edition by Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein.

I strongly suggest you to watch the following video lectures as soon as possible.

References

Introduction to Algorithms, 3rd Edition, Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein, The MIT Press, 2009 (Amazon) [CCLR]
Algorithms, 4th Edition, Robert Sedgewick, Kevin Wayne, Addison-Wesley Professional, 2011 (Amazon) [RS]
Algorithms, Sanjoy Dasgupta, Christos Papadimitriou, Umesh Vazirani, McGraw-Hill, 2006. (Amazon) [DPZ]
Programming Challenges: The Programming Contest Training Manual, Steven S. Skiena, Miguel A. Revilla, Springer, 2003 (Amazon) [SR]
Competitive Programming 4: The New Lower Bound of Programming Contests, Steven Halim, Felix Halim, (here) [HH]
Guide to Competitive Programming: Learning and Improving Algorithms Through Contests. Second Edition, Antti Laaksonen, Springer, 2020 (here) [L]

Rust

C++

The C++ Programming Language, 4th Edition, Bjarne Stroustrup, Addison-Wesley Professional, 2013 (Amazon)
A Tour of C++, 2nd Edition, Bjarne Stroustrup, Addison-Wesley Professional, 2018 (Amazon)
The C++ Standard Library: A Tutorial and Reference, 2nd Edition, Nicolai M. Josuttis, Addison-Wesley Professional, 2012 (Amazon)

Useful links

Erik D Demaine, Srini Devadas, Nancy Ann Lynch, "MIT Design and Analysis of Algorithms", MIT Algorithm course which includes video lectures
Tim Roughgarden, "Algorithm specialization", Coursera
Visualgo: visualising data structures and algorithms through animation
Geeks for Geeks: Company interviews preparation
Interviews common coding questions
How to: Work at Google — Example Coding/Engineering Interview Video
Google's Code Jam
Topcoder
Codeforces
LeetCode
HackerRank
Geeks for Geeks
LeetCode
CodeChef - Data Structures and Algorithms links
Geeks for Geeks: Top 10 Algorithms and Data Structures for Competitive Programming
List of resources for competitive programming

Lectures

Date	Lecture	References	Problems
15/09/2022	Introduction	Slides	Leaders in array (solution), Kadane's algorithm (solution), and Missing number in array (solution)
19/09/2022	Solutions of Trapping rain water and Sliding window maximum	Rossano's notes*	Trapping rain water (solution), and Sliding window maximum (solution)
22/09/2022	Analysis and correctness of Sliding window maximum. Brief introduction to Rust.		Next greater element and Towers (solution)
29/09/2022	Searching and Sorting: Binary Search, Merge Sort, QuickSort, Counting Sort, and Radix Sort	Rossano's notes*. [CCLR] Chapters 2.3, 7, and 8. Binary search. Exponential search. Interpolation search (optional)	The Monkey and the Oiled Bamboo
03/10/2022	Searching and Sorting: Binary Search, Merge Sort, QuickSort, Counting Sort, and Radix Sort		Inversion count and Two Types of Spells
05/10/2022	Hands-On 1. Deadline: 19/10/2022
10/10/2022	Trees: representation, traversals, and Binary Search Tree	Rossano's notes*. [CCLR] Chapters 10.4 and 12.	Frogs and Mosquitoes
13/10/2022	Lecture Cancelled!
17/10/2022	Trees: representation, traversals, and Binary Search Tree	Rossano's notes*. Tree traversals.	Maximum path sum (solution) and Longest k-Good Segment
20/10/2022	Trees: representation, traversals, and Binary Search Tree	Euler Tour. Two pointers technique.
24/10/2022	(Static) Prefix sum	Rossano's notes*	Ilya and Queries (solution), Number of ways (solution), and Little girl and maximum sum (solution)
27/10/2022	Segment Trees	Segment Tree: description, tutorial 1, tutorial 2, tutorial 3, video, visualgo, slides and code.	Solve Nested segments with Segment trees.
31/10/2022	Segment trees: Applications
03/11/2022	Segment Trees: Lazy Propagation and Persistency	Segment Tree: description, tutorial 1, tutorial 2, tutorial 3, video, visualgo, slides and code. Lazy propagation: tutorial and video.	Circular RMQ
07/11/2022	Exercises		Triplets (Text and TestSet) and Smaller Values (Text and TestSet)
10/11/2022	Hands-On 2. Deadline: 23/11/2022
14/11/2022	Static RMQ with sparse table	RMQ and sparse table: tutorial 1, tutorial 2, paper, and code. Static RMQ in 2n + o(n) bits and constant time(optional).
17/11/2022	Mo's algorithm on sequences and trees	Rossano's notes*. Mo's Algorithm: Sequences and Trees	Powerful array and Tree and queries
21/11/2022	Dynamic Programming: Fibonacci numbers, Rod cutting, and Shortest path on a DAG	Rossano's notes* (or pdf). [CCLR] Chapter 15.
24/11/2022	Dynamic Programming: Minimum cost path and Longest common subsequence	Rossano's notes* (or pdf). Martin Gardner on Minimum cost path.	Longest common subsequence and Minimum number of jumps
28/11/2022	Dynamic Programming: 0/1 Knapsack, Fractional knapsack, and Subset sum.	Rossano's notes* (or pdf). 0/1 Knapsack problem: tutorial	Subset sum and 0-1 knapsack
01/12/2022	Dynamic Programming: Longest increasing subsequence and Coin change	Rossano's notes* (or pdf)	Longest increasing subsequence
05/12/2022	Dynamic Programming: Longest increasing subsequence, Longest bitonic subsequence, and Largest independent set on trees	Rossano's notes* (or pdf)	Longest bitonic subsequence
09/12/2022	Hands-On 3. Deadline: 23/12/2022

Lectures from past years

Date	Lecture	References	Problems
2021	Prefix sum: Binary Indexed Tree (aka BIT or Fenwick tree)	Rossano's notes*. BIT: description, tutorial, video, visualgo, and code.	Update the array (solution)
2021	Applications of BIT and Range update with BIT.	Rossano's notes*. Range updates on BIT. Tutorial. RMQ with BIT (optional)	Nested segments (solution) and Pashmak and Parmida's problem (solution)
2017	Simulation of the exam		Misha and forest
2017	Centroid Decomposition of trees	Centroid Decomposition of trees: here, here, here, and here
2017	String algorithms: Knuth-Morris-Pratt and Suffix array	Knuth-Morris-Pratt from [CLRS] Chapter 32.3. Knuth-Morris-Pratt. Optional: Rabin-Karp here from Algorithms on strings, trees, and sequences, D. Gusfield, Cambridge university press, here, and here. Suffix Array: Tutorial and implementation: here and here. Optional: Suffix Array in linear time here	Longest prefix suffix and Shift the string
2017	String algorithms: LCP array, trie and ternary search trie	Computing LCP array: Kasai et al.'s algorithm and here. Ternary search trie and a video.
2018	Standard Template Library (STL)	Slides. Tutorial and STL algorithms	Megacity (solution), Find pair (solution), and Two heaps (solution)
2018	Standard Template Library (STL). Coding	Slides
2018	Heavy-light Decomposition of trees. This lecture is not mandatory.	Heavy-light Decomposition of trees: here, here, and here.	QTREE, QTREE2, QTREE3, GOT, and Chef and the tree.
2021	Greedy algorithms: Activity Selection, Job sequencing, and Fractional knapsack problem	Rossano's notes*. Notes by Jeff Erickson. Job sequencing. Fractional Knapsack Problem	N meetings in one room, Magic numbers, Wilbur and array, and Alternative thinking
2019	Greedy Algorithms: Boxes and Hero	Rossano's notes*. Boxes and Hero. Huffman code: Section 7.4 in Notes by Jeff Erickson (optional).	Lexicographically maximum subsequence, Woodcutters, and Queue
2021	Dynamic Programming: Edit distance, Longest palindromic subsequence, and Weighted job scheduling	Rossano's notes* (or pdf)	Edit distance, Vertex cover, and Longest palindromic subsequence
2021	Graph algorithms: BFS, DFS, and Topological Sort	Rossano's notes*. [CCLR] Chapter 22	X total shapes, IsBipartite, and Fox and names
2021	Graph algorithms: Strongly Connected Components and Single-Source Shortest Path	Rossano's notes*. [CCLR] Chapters 22 and 23	Learning languages and Checkposts
2019	Graph algorithms: Minimum Spanning Tree (and Disjoint Sets data structures)	Rossano's notes*. [CCLR] Chapters 21 and 23. Kruskal: code, Disjoint Set: tutorial	Minimum spanning tree

* Notes marked with "Rossano's notes" are rough and non-exhaustive notes that I used while lecturing. Please use them just to have a list of the topics of each lecture and use other reported references to study these arguments.

rossanoventurini / CompetitiveProgramming