Sage-Tips

What is Precomputation in programming?

In algorithms, precomputation is the act of performing an initial computation before run time to generate a lookup table that can be used by an algorithm to avoid repeated computation each time it is executed.

What does constraints mean in competitive programming?

Constraints tell you the upper and lower limit of inputs coming in. For eg. 1 <= T <=2000 would mean that the input for T would be between 1 and 2000.

What is Precomputation attack?

Precomputation attacks fall in the memory-intensive category. They take a source dictionary, hash every entry, and store the results. To guess the string used to generate a hash, the attacker looks up the hashed value in the precomputed table and checks the corresponding value that produced it.

Can we use multi threading in competitive programming?

Today, the industry tries to overcome the processing speed limits with concurrent, multi-threaded programs. Maybe competitive programming could enable some multi-threading capabilities, but that would be unfair with older (or not so well supported languages).

What is pre computed?

precompute. (ˌpriːkəmˈpjuːt) adj. (Banking & Finance) in which annual interest on a loan is computed in advance and either removed in advance from the total sum of the loan given or automatically built into monthly repayments.

Why are constraints in programming important?

Constraints direct us to think of a feasible solution. We must keep the constraints in our mind before framing the algorithm for a problem. Analyzing the constraints can give us crucial information, like the possible edge cases and the expected time complexity of the solution.

What do you do with constraints in programming?

Instead of defining a set of instructions with only one obvious way to compute values, constraint programming declares relationships between variables within constraints. A final model makes it possible to compute the values of variables regardless of direction or changes.

What is a rainbow table cryptographic attack?

A rainbow table attack is a password cracking method that uses a special table (a “rainbow table”) to crack the password hashes in a database. After the user enters their password to login, it is converted to hashes, and the result is compared with the stored hashes on the server to look for a match.

What are the advantages and disadvantages of rainbow tables?

Advantages and Disadvantages of Rainbow Table Attacks

• Hacker attacks using Rainbow Tables have the advantage of most data being pre-computed, resulting in an easy hack access.
• Another crucial advantage using of Rainbow Tables is the ability of authentication without serious obstacles.

What is precomputation in computer architecture?

Precomputation is the act of performing an initial computation before run time to generate a lookup table that can be used by an algorithm to avoid repeated computation each time it is executed. In 3D animation trignometric functions are used very often.

What is precomputation in machine learning?

Broadly, precomputation is when you divide your algorithm into phases, and in some earlier phase of the algorithm, you are doing some general computation that produces some data from the input, and then in some later phase, you use the previously computed data in order to speed up calculations.

What are the limitations of programming competitions?

In most competitions your code is executed in the online judge environment, which limits what tools you can use – for example, typically system calls and disk access are limited. Multithreading is usually not supported, as most competitions require a good single-core algorithm.

What is the most difficult task faced while doing competitive programming?

Generally, while doing competitive programming problems on various sites, the most difficult task faced is writing the code under desired complexity otherwise the program will get a TLE ( Time Limit Exceeded ). A naive solution is almost never accepted.