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Further practice

Questions

Given a number as input, count the number of bits with value 1 (e.g. 0101 – 2, 1111 – 4).
Given a number as input, check if it’s a power of 2. Can you do that without looping?
How can we detect whether a graph contains cycles?
How can we check whether there’s a path between two vertices, in a directed graph?
Given the tree root node and the destination node – find out the level of the destination node.

Puzzles

Minimum number of moves to make two strings equal

Given two strings A and B of equal lengths, containing only lower case letters, your job is to count the minimum number of changes required on string A to make it equal to string B.

Count number of trailing zeros for the factorial result of a given n (n!)

Given n a positive number bigger than 1, count the number of trailing zeros of the factorial result.
Assuming n is 10, the factorial result will be 1*2*3* … * 10.

Print reverse a linked list

Given a linked list and having access only to the head element, print the reverse list without using recursion or extra allocated space.

Print all permutations of a given string

A permutation is a rearrangement of the elements. A string of length n has n! permutations.
Assuming our string is ABC, the following permutations are possible: {ABC, ACB, BAC, BCA, CAB, CBA}.
We can see that we started with A and shuffled the letters, then we moved B as first position and did the same, and then the same way for C.

Algorithmic problems

Longest Increasing Subsequence

Having Longest Common Sequence in mind – calculate the longest increasing subsequence (the length of the longest subsequence in which all elements are sorted in increasing order).

Job Sequencing

Given an array of jobs (each with their own deadline and with a given profit only if the job is finished before the deadline), and knowing that every job takes at least one unit of time (minimum deadline is 1) and that only one job can be scheduled at a time – Create an algorithm to maximize total profit.

Count all possible paths between two vertices

Given a directed graph, that does not contain a cycle – count the number of paths that exist between two vertices.

Exercises

Linux

I suggest installing Ubuntu on your personal computer, or searching online for a playground / practical course. There are a few basic commands that you must know by heart, such as copying or moving files, creating and removing files and directories, reading the content of a file, executing binaries or changing the access permissions of a file.
The next thing you should do after you exercise with such commands, is to write them into a script and execute it.
This will get you used to creating scripts for repetitive commands.

Python

Python has increased in popularity lately, and I recommend learning it, because it excels at small scripts, due to its powerful libraries which allows some rapid development. Take a text file with lot of information from it and:

Read in the file
Create a collection of words and their occurrences
Create a collection of anagrams
Create a collection of words and the positions in which they occur (line#, word position)
Remove all of the white space from the file
Write all of the above data to their own files

C# (+SQL)

Create a timer and do something on process event
Create delegates / events and add them in the code
Create a unit test for a public function
Create a basic GUI (button, label, progressbar - that increases on timer tick)
Use LINQ statement to calculate some specific values based on collection data
Encrypt and decrypt a password using Security namespace
Create a database and connect to it
Use SQL to make DB requests (CRUD)

C++

Create a library and a new project, link with your library (both statically and dynamically).
Create a small application (client/server) that communicate with each other through sockets.
Integrate makefile with the build project and make it cross-platform compilable.
Integrate some open-source library into your project, such as curl, rapidjson, zlib.

QT

Create a basic GUI application and add a class with signals and slots.
Emit a signal on button press that changes the color of a button.
Change the button color on mouse hover, on left and right click, on entering and leaving the area.

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Badea Robert