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Problem Statement for "SquareFreeString"

Problem Statement

We say that a string S is a square if it has the form TT, where T is some non-empty string. In other words, a square is a string that is a concatenation of two copies of the same non-empty string. For example, the strings "aa", "bbbb", and "beriberi" are squares.

A string is called square-free if none of its substrings is a square. For example, the string "abca" is square-free. (The substrings of this string are the strings "a", "b", "c", "a", "ab", "bc", "ca", "abc", "bca", and "abca". None of these strings is a square.)

You are given a String s. Return "square-free" if s is square-free. Otherwise, return "not square-free". Note that the return value is case-sensitive.

Definition

Class:
SquareFreeString
Method:
isSquareFree
Parameters:
String
Returns:
String
Method signature:
String isSquareFree(String s)
(be sure your method is public)

Constraints

  • s will consist only of lowercase English letters ('a'-'z').
  • The length of s will be between 1 and 50, inclusive.

Examples

  1. "w"

    Returns: "square-free"

  2. "cb"

    Returns: "square-free"

  3. "qok"

    Returns: "square-free"

  4. "aegi"

    Returns: "square-free"

  5. "oqquy"

    Returns: "not square-free"

  6. "ulhpnm"

    Returns: "square-free"

  7. "hncmexsslh"

    Returns: "not square-free"

  8. "psdurqrqdvmqgwplcktqejbhngvkjnrldskaxclvnblz"

    Returns: "not square-free"

  9. "wobervhvvkihcuyjtmqhaaigvahheoqleromusrartldojsjvy"

    Returns: "not square-free"

  10. "fcliblymyqckxvieotjotiqwtyznhvuhbaixwqnsytx"

    Returns: "square-free"

  11. "wobervhvkihcuyjtmqhaigvaheoqleromusrartldojsjvynfs"

    Returns: "square-free"

  12. "aydyamrbnauhftmphyroyqg"

    Returns: "square-free"

  13. "hncmexslhs"

    Returns: "square-free"

  14. "ijvxljt"

    Returns: "square-free"

  15. "qok"

    Returns: "square-free"

  16. "sijcwpcfrnlaqwdjftpxzrbtzil"

    Returns: "square-free"

  17. "cwlqeyjcukhsmumtesyoqjisfxqfgwjhx"

    Returns: "square-free"

  18. "rajcqwqnqmshmerpvjyfepxwpxyldzpzhctqjnstxyfmlhiyt"

    Returns: "square-free"

  19. "vmluxpwzhga"

    Returns: "square-free"

  20. "hncmexsxss"

    Returns: "not square-free"

  21. "rtcjbjlbtjrtcjbjlbtj"

    Returns: "not square-free"

  22. "wobervhvkihcuyjtmqhaigvaheoqleromusrartldoosjvynfs"

    Returns: "not square-free"

  23. "xiwpcfsmzenbvpdfpnduqienbvpdfpnduqiwngqb"

    Returns: "not square-free"

  24. "cwlqeyjcukhsmumtelqeyjcukhsmumtex"

    Returns: "not square-free"

  25. "qoo"

    Returns: "not square-free"

  26. "xtejpsfqyiplmyzuotbymtkcmuotbymtkcmrufgsyxmnqmc"

    Returns: "not square-free"

  27. "fcliblymyqckxvieotjotiqwtyznhtyznhixwqnsytx"

    Returns: "not square-free"

  28. "iraqgobfiaqgobfirhjcigigym"

    Returns: "not square-free"

  29. "porbdorbduvtu"

    Returns: "not square-free"

  30. "bobo"

    Returns: "not square-free"

    "bobo" = T + T, where T = "bo", so it is not square-free.

  31. "apple"

    Returns: "not square-free"

    Substring "pp" is a square.

  32. "pen"

    Returns: "square-free"

    "pen" does not contain any substrings that are squares.

  33. "aydyamrbnauhftmphyrooyq"

    Returns: "not square-free"

  34. "qwertyuiopasdfghjklzxcvbnm"

    Returns: "square-free"

  35. "abb"

    Returns: "not square-free"

  36. "a"

    Returns: "square-free"

  37. "abca"

    Returns: "square-free"

  38. "ssa"

    Returns: "not square-free"

  39. "bobk"

    Returns: "square-free"

  40. "abcdeezyok"

    Returns: "not square-free"

  41. "xdyrthsyu"

    Returns: "square-free"

  42. "acba"

    Returns: "square-free"

  43. "abcabc"

    Returns: "not square-free"

  44. "bab"

    Returns: "square-free"

  45. "abc"

    Returns: "square-free"

  46. "abcdd"

    Returns: "not square-free"

  47. "aa"

    Returns: "not square-free"

  48. "bkmbod"

    Returns: "square-free"

  49. "abcadc"

    Returns: "square-free"

  50. "abcdefafagheih"

    Returns: "not square-free"

  51. "abcdab"

    Returns: "square-free"

  52. "bolo"

    Returns: "square-free"

  53. "aaa"

    Returns: "not square-free"

  54. "dfidhrgneijrwsjackjackjierkf"

    Returns: "not square-free"

  55. "aba"

    Returns: "square-free"

  56. "asdfghjklqwertyuiopzxcvbnvcc"

    Returns: "not square-free"

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