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EDAF05 - Exercises

Algoritmer datastrukturer och komplexitet

How these exercises work

Standard in and Standard out in a terminal

The labs in this course are on the format that you should write a program that solves an algorithmic problem, by reading from standard in and writing a correct answer to standard output.

Environment assumptions

We assume that you use a terminal with a bash-like shell. This is the standard shell for most Linux distributions, and macOS. For windows you can download GitBash.

Let’s say you have written some code in a file, that has a main-function, and you have compiled it with javac, creating a file Solver.class.

There exists an input file that is called, and the correct output is in example.ans. Then your program will be checked by running java Solver < > example.out in your terminal. This means that the content of is sent to your program Solver on stdin, and the output is saved in the file example.out. Then we can check if your program produced the correct output by using the program diff. Running diff example.out example.ans will print nothing if the content is the same (your program worked as excepted) and will print the difference between the files if they differ.

Good News

There exists a website called Kattis (, which has a lot of different algorithmic problems, and uses the same execution-model that we do.

The problems on Kattis can be used as exercises for the course.

If you want to know how to read from stdin and print to stdout in your preferred programming language you can check out their help page. There is also som links to for example how judging is done explaining what results you can get when you submit your code:

  • Accepted - Your code was correct and you get points
  • Wrong Answer - Your code produced an incorrect answer on at least one of the test cases
  • Time Limit Exceeded - Your code didn’t finish in time
  • Run Time Error - Your code crashed while running one of the testcases
  • Compile Error - Your code didn’t compile

To use Kattis you need an account. You can either log in via Google/Facebook/LinkedIn, or create one.

If you have problems solving some of the exercises you can join our discord and ask for help in a dedicated channel for the course!


1. Introduction


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