# 4 Keys Keyboard

• Please have someone to check the grammar and make sure your staff can understand what the article says before you promote it as the solution.

• @Nio I am writing the articles. What specifically is wrong with it? English is my native language.

• Hi Thanks for the article. Is there any way find out the use of q,what is the reason behind

``        return best[N - 5*q] << 2 * q;`````

• In approach #2, can you mention when N. Is N the size of the array?

• worst solution article I ever seen

• Solutions are correct. The writing is unclear.

• It's better to rewrite the article.

• Something is wrong here: for N=11 the answer as per solution above is 27. Assuming 2 keys are consumed with Ctrl-A and Ctrl-C.
How? M=5 K=4 gives 25
M=6 K=3 gives 24
M=7 K=2 gives 21
M=4 K=5 gives 24

Maybe I am missing something...

• This post is deleted!

• <Multiply (k+1 keypresses): Multiply M by k>

is wrong. In order to multiply current `M` letters on the screen k times, you need k + 2 key presses: one key2, one key3, and k key4.

• I didn't read the mathematical method part. But the dynamic programming method part needs way more explanations. I feel this part is a simplified version of the article on GeeksForGeeks without all critical points.

• The explanation of mathematical part proves that we can do the best[K] = best[K-5] * 4 trick when K >= 30 + 20 + 6 + 5, but I don't see how it can prove it is true for as low as K == 16?

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