CodeForces | designed problems that I solved in CodeForces contests | Learning library

I would say CTF challenges are a good way to learn. https://tryhackme.com/ is a good place to start. Most of the rooms are aimed at beginners and it will give you a good understanding, of some of the programs you will use like nmap, burpsuite and wireshark. https://www.hackthebox.eu/ is a good place, when you are a bit more experienced.

I am also gonna share some GitHub links, you might find interesting:

• https://github.com/Hack-with-Github/Awesome-Hacking
• https://github.com/OWASP/CheatSheetSeries
• https://github.com/gerryguy311/Free_CyberSecurity_Professional_Development_Resources

Here, you trying to access vec[-1], which leads to out of range subscript.

Try to run this and look for output:

As the error says:

The nested loop used to find MINID makes the runtime quadratic in n:

Don't use too many intermediate floating variables to get to the final answer. Small inaccuracies when add up lead to huge inaccuracy which you can clearly see in the expected and real output in your question. What you can do is to minimize these intermediate floating variables. For example

An other formula for the product of the divisors of N is N ** (D/ 2), where D is the number of divisors and may be found from your map count by taking the product of entry->second + 1 for every entry.

This does raise the question of what to do when D is odd, which it would be if N is a perfect square. In that case it is easy to compute sqrt(N) (the exponents would all be even, so you can halve them all and take the product of the primes to half of their original exponents), and then raise sqrt(N) to the power of D. Essentially this changes N ** (D / 2) into (N ** (1 / 2)) ** D.

For example if N = 2 * 3 * 2 = 12 (one of the examples), then D will be (2 + 1) * (1 + 1) = 6 and the product of divisors will be 12 ** (6 / 2) = 1728.

Computing N (or its square root) should done modulo mod. Computing D should be done modulo mod - 1 (the totient of mod, mod is a prime so its totient is just one less). mod - 1 is even, so we could not have computed the modular multiplicative inverse of 2 to "divide" D by 2 that way. When N is a square then AFAIK we're really stuck with computing its square root (that's not so bad, but multiplying by a half would have been easier).

arra[i-1] with i=0 is out-of-range and using such out-of-range element invokes undefined behavior.

Fix the loop for(i=n-1; i>=0; i--){ not to cause out-of-range access.

It may be better to use the standard qsort() function for sorting than writing your own sorting algorithm.

not the best and efficient solution but if you just want to show some data like username or email you can do it like this:

I'm not sure if this is more of a stackoverflow question or not, but I could be wrong. . . Based on your question and its usage I would prefer a breakdown of the word "lexicographically".

The root appears to be "lexicon", which we can see by this reference the definition is:

"a book containing an alphabetical arrangement of the words in a language and their definitions"

OR

"the vocabulary of a language, an individual speaker or group of speakers, or a subject"

OR (more related to computers)

"the total stock of morphemes in a language"

In this pdf the author says,

"The lexicon of a computer language is its total inventory of words and symbols."

Next, we want to look at the word "lexicography", this is the next layer to our process of building the word up from the root. First, let us look at the general definition. According to Merriam-Webster in this reference we see that lexicography is defined as such:

"the editing or making of a dictionary"

OR

"the principles and practices of dictionary making"

In this reference regarding Computation Lexicography the author states, "Computational Lexicology is the use of computers in the study of the lexicon. It has been more narrowly described by others (Amsler, 1980) as the use of computers in the study of machine-readable dictionaries."

The next-to-last step is to look at the word without its description of the action occurring, that would be "lexicographic", as in lexicographic order. In this reference we see, "In mathematics, the lexicographic or lexicographical order (also known as lexical order, or dictionary order) is a generalization of the alphabetical order of the dictionaries to sequences of ordered symbols or, more generally, of elements of a totally ordered set."

Lastly, we can see that the word is an adverb since in the example sentence it is describing the action that is occurring - also we see the use of "-ly" at the end of the word.

It would appear that Petya would like to compare the two strings alphabetically and with regard to their potentially symbolic, or definitive, meaning within the dictionary of lexicons from which they exist.

A fun little analysis project that took me on.