Statistics

Problem Statement for "PickTwoCards"

Problem Statement

You are given a String cards, where each character represents the color of a card. You then select two of those cards at random. Return the probability that they are the same color.

Definition

Class:
PickTwoCards
Method:
equalProbability
Parameters:
String
Returns:
double
Method signature:
double equalProbability(String cards)
(be sure your method is public)

Notes

  • A return value that is less than 1e-9 absolute or relative error is considered correct.

Constraints

  • cards will contain between 2 and 50 characters, inclusive.
  • Each character of cards will be between 'A' and 'Z', inclusive.

Examples

  1. "AAB"

    Returns: 0.3333333333333333

    There are three ways to pick two cards, one of which is both "A" cards.

  2. "ABC"

    Returns: 0.0

    Can't get two the same when there's only one of each.

  3. "AA"

    Returns: 1.0

    Only two cards to choose, so we always get a matched pair.

  4. "ABABA"

    Returns: 0.4

  5. "ABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGH"

    Returns: 0.12

  6. "MMSTYQWMCQMVAVOLQAWIMO"

    Returns: 0.07359307359307359

  7. "DJWZEABJYFNRRETBBWA"

    Returns: 0.04678362573099415

  8. "LPQQANSMXZUYYDPKBRRLAHOQMEWGWYVLLUXNSFY"

    Returns: 0.032388663967611336

  9. "IPMYKPSOPIZKEOTEAZDVQLQYEINEGBSWS"

    Returns: 0.03787878787878788

  10. "DLVQ"

    Returns: 0.0

  11. "XLIRNYKHWATNS"

    Returns: 0.012820512820512822

  12. "CZXYN"

    Returns: 0.0

  13. "CCNHOQDRCLHIKTGJITCATAQDMOAUPBFMIWDVXAD"

    Returns: 0.037786774628879895

  14. "VTEKTKCYVSRDWNABLKVZPIBBFUAOQLLHQFEAVFKCLBZWKC"

    Returns: 0.04057971014492753

  15. "VVBJNFDHMRDFYJOIKGKNQIAGGZTNOJFRD"

    Returns: 0.03787878787878788

  16. "HVPIQENJPGWJLCVZCAWRPKXQKWZEFQXSZQQUBWHMTBSJEATPPF"

    Returns: 0.036734693877551024

  17. "LHAAXXZYTEJDZJEJULBXFTKXOROMJDJPAQLKYPSWCYNHKYSZZQ"

    Returns: 0.036734693877551024

  18. "DOHUSXCMGJMOQVTDJXTLETEVGFCNPYOMSEGASWTNVDMMPKXMQU"

    Returns: 0.03918367346938775

  19. "CFFTKJMNMUPWHUAVLOTLNEGPBGSFWIQXVPMGNLVRFIGSGGFSPO"

    Returns: 0.04163265306122449

  20. "XXJWXZPSDRHQEERBRHTIZTBFEYNJUBAPIVSAMTPHXSSAYSBOOF"

    Returns: 0.037551020408163265

  21. "KWFMEVDRYLGXCRRHILROYSLLHABHLWZUPNPTCJOEIBQVQUQJGK"

    Returns: 0.02857142857142857

  22. "CXQORKUFDUWFCMMIOBYEZXMFXBQUMKSAADXWYZYJIEKKMVOJDM"

    Returns: 0.04163265306122449

  23. "IIGTFLKRPUASTBVEYOQKOCOWVMBTBNGQAJKRUKSKOIIOILRJRQ"

    Returns: 0.04244897959183674

  24. "UNCMFTJXSKRPCNJRKREKNWFVGUAOJVSBKXMDYWEXKMZAWSGBYT"

    Returns: 0.03346938775510204

  25. "RNGBYHGFKTVNXSPEEAGTNMGZAWFZONYPQNAOEVOVSQTDPZCIHO"

    Returns: 0.036734693877551024

  26. "PINTUI"

    Returns: 0.06666666666666667

  27. "ABDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD"

    Returns: 0.9158186864014801

  28. "AAABBCDEFG"

    Returns: 0.08888888888888889

  29. "AAABBBAABB"

    Returns: 0.4444444444444444

  30. "AAKRITUA"

    Returns: 0.10714285714285714

  31. "ABABCDEEF"

    Returns: 0.08333333333333333

  32. "ABCDABCDEFGHABCDEFHIHN"

    Returns: 0.07359307359307359

  33. "AAAAAAAAAAAAA"

    Returns: 1.0

  34. "AAAAAAAAAAAAAEEEE"

    Returns: 0.6176470588235294

  35. "AVDDDDDDDASDANANANANDBANDBANDBANBDNAD"

    Returns: 0.23573573573573572

  36. "ABABAABBBSSS"

    Returns: 0.28787878787878785

  37. "ABAAC"

    Returns: 0.3

  38. "AABA"

    Returns: 0.5

  39. "ABABABBBA"

    Returns: 0.4444444444444444

  40. "AGHUHHX"

    Returns: 0.14285714285714285

  41. "PINTUIAI"

    Returns: 0.10714285714285714

  42. "AAAABBBCDFRGHTKJLF"

    Returns: 0.06535947712418301

  43. "ABABGGF"

    Returns: 0.14285714285714285

  44. "ABAACC"

    Returns: 0.26666666666666666

  45. "ABACBA"

    Returns: 0.26666666666666666

  46. "AAABBABABCCDB"

    Returns: 0.2692307692307692

  47. "ABBABAABABCCCAA"

    Returns: 0.3238095238095238

  48. "AAAAVVVBBB"

    Returns: 0.26666666666666666

  49. "ABBABAABABC"

    Returns: 0.36363636363636365

  50. "ABABABAC"

    Returns: 0.32142857142857145

  51. "ABCZABCZAAAAA"

    Returns: 0.3076923076923077

  52. "AABAOKDFOJSDNFIEADFJSIHJIASDOJ"

    Returns: 0.07816091954022988

  53. "ABCDEFFFGGGGH"

    Returns: 0.11538461538461538

  54. "ABCAB"

    Returns: 0.2

  55. "ABA"

    Returns: 0.3333333333333333

  56. "ABBBCCADDE"

    Returns: 0.13333333333333333

  57. "AAAAZBZWWWW"

    Returns: 0.2363636363636364

  58. "AABAQ"

    Returns: 0.3

  59. "AAAABBAQ"

    Returns: 0.39285714285714285

  60. "SURABHINEHANITINPURNIMA"

    Returns: 0.07114624505928854

  61. "NEHAPURNIMASURABHINITIN"

    Returns: 0.07114624505928854

  62. "NITINPURNIMANEHASURABHI"

    Returns: 0.07114624505928854

  63. "ABABABABBBBBCXYSZ"

    Returns: 0.25

  64. "AAA"

    Returns: 1.0

  65. "ABABACCCCCCCCCCC"

    Returns: 0.49166666666666664

  66. "ABABABCCC"

    Returns: 0.25

  67. "AAABBBCCC"

    Returns: 0.25

  68. "AB"

    Returns: 0.0

  69. "ABCA"

    Returns: 0.16666666666666666

  70. "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"

    Returns: 1.0

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