Line 2: Line 2:
  
 
A
 
A
 +
 
Ctrl+A
 
Ctrl+A
  
 
Ctrl+C
 
Ctrl+C
 +
 
Ctrl+V
 
Ctrl+V
 +
 
where CTRL+A, CTRL+C, CTRL+V each acts as one function key for “Select All”, “Copy”, and “Paste”
 
where CTRL+A, CTRL+C, CTRL+V each acts as one function key for “Select All”, “Copy”, and “Paste”
 
operations respectively.
 
operations respectively.
 +
 
If you can only press the keyboard for N times (with the above four keys), please write a program to produce
 
If you can only press the keyboard for N times (with the above four keys), please write a program to produce
 
maximum numbers of A. If possible, please also print out the sequence of keys.
 
maximum numbers of A. If possible, please also print out the sequence of keys.

Revision as of 16:13, 17 June 2014

Imagine you have a special keyboard with the following keys:

A

Ctrl+A

Ctrl+C

Ctrl+V

where CTRL+A, CTRL+C, CTRL+V each acts as one function key for “Select All”, “Copy”, and “Paste” operations respectively.

If you can only press the keyboard for N times (with the above four keys), please write a program to produce maximum numbers of A. If possible, please also print out the sequence of keys. That is to say, the input parameter is N (No. of keys that you can press), the output is M (No. of As that you can produce).

Solution by Arjun Suresh

<syntaxhighlight lang="c" name="printa">

  1. include <stdio.h>

int main() {

   unsigned long N, M, i;
   printf("Enter N: ");
   scanf("%lu", &N);
   if(N <= 6)
   {
       M = 6;
       for(i = 0; i < N; i++)
       printf("A\n");
   }

   else if (N % 3 == 0)
   {
       M = 3 * (1L<< (N-3)/3); //1<<x gives pow(2,x) and I'm too lazy to include math.h
       for(i = 0; i < 3; i++)
           printf("A\n");
       for(i = 1; i < N/3; i++)
       {
           printf("Select\n");
           printf("Copy\n");
           printf("Paste\n");
       }
   }

   else 
   {
       M = 4 * (1L << (N-4)/3) + (N-4)%3; //1<<x gives pow(2,x)
       for(i = 0; i < 4; i++)
           printf("A\n");

       for(i=0; i < (N-4)/3; i++)
       {
           printf("Select\n");
           printf("Copy\n");
           printf("Paste\n");
       }

       for(i = 0; i < N%3; i++)
           printf("A\n");
   } 
   printf("\nM = %lu\n", M);

} </syntaxhighlight>




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Imagine you have a special keyboard with the following keys:

A

Ctrl+A

Ctrl+C

Ctrl+V

where CTRL+A, CTRL+C, CTRL+V each acts as one function key for “Select All”, “Copy”, and “Paste” operations respectively.

If you can only press the keyboard for N times (with the above four keys), please write a program to produce maximum numbers of A. If possible, please also print out the sequence of keys. That is to say, the input parameter is N (No. of keys that you can press), the output is M (No. of As that you can produce).

Solution by Arjun Suresh[edit]

<syntaxhighlight lang="c" name="printa">

  1. include <stdio.h>

int main() {

   unsigned long N, M, i;
   printf("Enter N: ");
   scanf("%lu", &N);
   if(N <= 6)
   {
       M = 6;
       for(i = 0; i < N; i++)
       printf("A\n");
   }

   else if (N % 3 == 0)
   {
       M = 3 * (1L<< (N-3)/3); //1<<x gives pow(2,x) and I'm too lazy to include math.h
       for(i = 0; i < 3; i++)
           printf("A\n");
       for(i = 1; i < N/3; i++)
       {
           printf("Select\n");
           printf("Copy\n");
           printf("Paste\n");
       }
   }

   else 
   {
       M = 4 * (1L << (N-4)/3) + (N-4)%3; //1<<x gives pow(2,x)
       for(i = 0; i < 4; i++)
           printf("A\n");

       for(i=0; i < (N-4)/3; i++)
       {
           printf("Select\n");
           printf("Copy\n");
           printf("Paste\n");
       }

       for(i = 0; i < N%3; i++)
           printf("A\n");
   } 
   printf("\nM = %lu\n", M);

} </syntaxhighlight>




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