COCI '13 Contest 3 #1 Riječi

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Points: 5 (partial)
Time limit: 1.0s
Memory limit: 32M

Problem type

One day, little Mirko came across a funny looking machine! It consisted of a very very large screen and a single button. When he found the machine, the screen displayed only the letter A. After he pressed the button, the letter changed to B. The next few times he pressed the button, the word transformed from B to BA, then to BAB, then to BABBA. When he saw this, Mirko realized that the machine alters the word in a way that all the letters B get transformed to BA and all the letters A get transformed to B.

Amused by the machine, Mirko asked you a very difficult question! After K times of pressing the button, how much letters A and how much letters B will be displayed on the screen?

Input Specification

The first line of input contains the integer K (1 \le K \le 45), the number of times Mirko pressed the button.

Output Specification

The first and only line of output must contain two space-separated integers, the number of letters A and the number of letters B.


In test data worth 20\% of total points, K will be less or equal to 10.

Sample Input 1


Sample Output 1

0 1

Sample Input 2


Sample Output 2

2 3

Sample Input 3


Sample Output 3

34 55


  • -1
    Wimfke  commented on June 12, 2022, 4:24 p.m. edited

    The last three test cases i didn't pass the time limit. How can I improve my speed? thanks

    the editorial helped. got it.

  • 0
    Omgydlord  commented on June 9, 2022, 7:56 p.m.

    I have been struggling with this one for two days. I can't figure out how to track the updates to the letters correctly.

    • -1
      jeano  commented on June 18, 2022, 5:30 p.m. edited

      Don't track them. At every iteration parse the string to count how many of 'A', 'B', and 'AB', you have. Then, create the next string, etc etc. But, this is not the best way to do this exercise. Instead, write down how many As and Bs you get at every iteration and you'll see a pattern emerge.

      • -1
        electrobird  commented on June 23, 2022, 2:07 a.m.

        Thank you for the tip. After reading this it took me little more than 5 minutes to resolve it.

  • 0
    stuart314159  commented on June 8, 2022, 2:04 p.m. edited

    The memory limit of 32M is insufficient if you try to generate the entire sequence of 'A's and 'B's in the test cases 9-11, at least in python. So instead of generating the sequence and then counting As and Bs, you might try counting the letters directly without generating the whole sequence of characters... Fibo, anyone? ;-)