Statistics

Problem Statement for "UnrepeatableWords"

Problem Statement

For a given integer k, we call a string S k-unrepeatable if there is no substring that appears k consecutive times in S.

For example, the string CCABAABAABAC is 4-unrepeatable. But it's not 3-unrepeatable, because the string ABA appears in it 3 times in a row. CCABAABACABA and ABABAABA are examples of 3-unrepeatable strings.

You are given three integers, k, n and allowed. Return the lexicographically smallest k-unrepeatable word of length n that uses only the first allowed uppercase characters of the English alphabet. If no such word exists, return the empty string.

Definition

Class:
UnrepeatableWords
Method:
getWord
Parameters:
int, int, int
Returns:
String
Method signature:
String getWord(int k, int n, int allowed)
(be sure your method is public)

Constraints

  • k will be between 2 and 10, inclusive.
  • n will be between 1 and 50, inclusive.
  • allowed will be between 1 and 26, inclusive.

Examples

  1. 3

    5

    2

    Returns: "AABAA"

    All lexicographically smaller strings of length 5 contain three consecutive occurrences of the letter A, so they aren't 3-unrepeatable.

  2. 3

    5

    1

    Returns: ""

    The only possible string is AAAAA, which is not 3-unrepeatable.

  3. 3

    10

    2

    Returns: "AABAABABAA"

  4. 3

    50

    2

    Returns: "AABAABABAABAABBAABAABABAABAABBAABAABABAABABBAABAAB"

  5. 4

    50

    3

    Returns: "AAABAAABAAABAAACAAABAAABAAABAAACAAABAAABAAABAAACAA"

  6. 4

    50

    26

    Returns: "AAABAAABAAABAAACAAABAAABAAABAAACAAABAAABAAABAAACAA"

  7. 2

    1

    1

    Returns: "A"

  8. 2

    1

    2

    Returns: "A"

  9. 10

    40

    26

    Returns: "AAAAAAAAABAAAAAAAAABAAAAAAAAABAAAAAAAAAB"

  10. 10

    40

    2

    Returns: "AAAAAAAAABAAAAAAAAABAAAAAAAAABAAAAAAAAAB"

  11. 10

    40

    3

    Returns: "AAAAAAAAABAAAAAAAAABAAAAAAAAABAAAAAAAAAB"

  12. 3

    49

    26

    Returns: "AABAABAACAABAABAACAABAABAADAABAABAACAABAABAACAABA"

  13. 10

    1

    26

    Returns: "A"

  14. 7

    48

    26

    Returns: "AAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAA"

  15. 7

    49

    1

    Returns: ""

  16. 7

    50

    2

    Returns: "AAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAABAA"

  17. 7

    50

    3

    Returns: "AAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAACA"

  18. 7

    49

    5

    Returns: "AAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAAC"

  19. 7

    49

    6

    Returns: "AAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAABAAAAAAC"

  20. 3

    2

    1

    Returns: "AA"

  21. 8

    49

    26

    Returns: "AAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABA"

  22. 8

    49

    13

    Returns: "AAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABA"

  23. 8

    50

    8

    Returns: "AAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAA"

  24. 2

    10

    10

    Returns: "ABACABADAB"

  25. 2

    3

    2

    Returns: "ABA"

  26. 2

    4

    2

    Returns: ""

  27. 2

    50

    9

    Returns: "ABACABADABACABAEABACABADABACABAFABACABADABACABAEAB"

  28. 8

    50

    7

    Returns: "AAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAAAAAAABAA"

  29. 3

    50

    20

    Returns: "AABAABAACAABAABAACAABAABAADAABAABAACAABAABAACAABAA"

  30. 5

    40

    20

    Returns: "AAAABAAAABAAAABAAAABAAAACAAAABAAAABAAAAB"

  31. 10

    50

    26

    Returns: "AAAAAAAAABAAAAAAAAABAAAAAAAAABAAAAAAAAABAAAAAAAAAB"

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