# How to print maximum number of A’s using given four keys

Let us consider, we will try to write the letter ‘A’, using the keyboard. Our goal is to use only four keys and try to write maximum ‘A’s on the text field. The keys are ‘A’, ‘C’, ‘V’ and ‘Ctrl’.

To write the maximum number of A, we will use Ctrl + A to select All, Ctrl + C to copy and Ctrl + V to paste.

## Input and Output

Input:
Number of keystrokes, say 7
Output:
Maximum Number of A's with 7 keystrokes is: 9
Press A three times. Then Ctrl+A, Ctrl+C, Ctrl+V, Ctrl+V

## Algorithm

keyNumbers(keyStrokes)

Input: number of keystrokes.

Output: Maximum number of letters using these keystrokes.

Begin
if keyStrokes <= 6, then
return keyStrokes

for n := 1 to 6, do
result[n-1] := n
done

for n := 7 to keyStrokes, do
result[n-1] := 0
for breakpoint := n-3 down to 1, do
curr := (n – breakpoint - 1)*result[breakpoint - 1]
if curr > result[n-1], then
result[n - 1] := curr
done
done
result[keyStrokes - 1]
End

## Example

#include<iostream>
using namespace std;

int keyNumbers(int keystrokes) {    //find number of 'A's using 4 types of keys
if (keystrokes <= 6)    //if keystrokes are less than 7
return keystrokes;

int result[keystrokes];    //store intermediate results
for (int n=1; n<=6; n++)    //upto 6 keystrokes, we need that number of keystrokes for max
result[n-1] = n;

for (int n=7; n<=keystrokes; n++) {    //for 7th to higher
result[n-1] = 0;    //initially store 0 as result
for (int breakPoint=n-3; breakPoint>=1; breakPoint--) {    //find breakpoint to select, copy and paste
int curr = (n-breakPoint-1)*result[breakPoint-1];
if (curr > result[n-1])
result[n-1] = curr;
}
}
return result[keystrokes-1];
}

int main() {
int keystrokes;
cout << "Enter Number of keystrokes: "; cin >> keystrokes;
cout << "Maximum Number of A's with "<<keystrokes << " keystrokes is: "<< keyNumbers(keystrokes)<<endl;
}

## Output

Enter Number of keystrokes: 7
Maximum Number of A's with 7 keystrokes is: 9
Samual Sam

Learning faster. Every day.