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Problem Statement for "AB"

Problem Statement

You are given two ints: N and K. Lun the dog is interested in strings that satisfy the following conditions:

  • The string has exactly N characters, each of which is either 'A' or 'B'.
  • The string s has exactly K pairs (i, j) (0 <= i < j <= N-1) such that s[i] = 'A' and s[j] = 'B'.

If there exists a string that satisfies the conditions, find and return any such string. Otherwise, return an empty string.

Definition

Class:
AB
Method:
createString
Parameters:
int, int
Returns:
String
Method signature:
String createString(int N, int K)
(be sure your method is public)

Constraints

  • N will be between 2 and 50, inclusive.
  • K will be between 0 and N(N-1)/2, inclusive.

Examples

  1. 3

    2

    Returns: "ABB"

    This string has exactly two pairs (i, j) mentioned in the statement: (0, 1) and (0, 2).

  2. 2

    0

    Returns: "BA"

    Please note that there are valid test cases with K = 0.

  3. 5

    8

    Returns: ""

    Five characters is too short for this value of K.

  4. 10

    12

    Returns: "BAABBABAAB"

    Please note that this is an example of a solution; other valid solutions will also be accepted.

  5. 2

    1

    Returns: "AB"

  6. 3

    0

    Returns: "BBA"

  7. 3

    1

    Returns: "BAB"

  8. 3

    3

    Returns: ""

  9. 4

    3

    Returns: "ABAB"

  10. 5

    6

    Returns: "AABBB"

  11. 6

    0

    Returns: "BBBAAA"

  12. 7

    16

    Returns: ""

  13. 8

    7

    Returns: "ABABBBAA"

  14. 9

    1

    Returns: "BBBBABAAA"

  15. 10

    12

    Returns: "BAABBABAAB"

  16. 11

    16

    Returns: "AABBABBBBAA"

  17. 12

    8

    Returns: "ABBBBABBAAAA"

  18. 13

    29

    Returns: "AAAABBBBBBABA"

  19. 14

    67

    Returns: ""

  20. 15

    21

    Returns: "AABBBABBBBBAAAA"

  21. 16

    97

    Returns: ""

  22. 17

    14

    Returns: "ABBBBABBBBBAAAAAA"

  23. 18

    20

    Returns: "AABBBBBBBABBAAAAAA"

  24. 19

    46

    Returns: "AAAABBBBABBBBBBAAAA"

  25. 20

    20

    Returns: "AABBBBBBBBBBAAAAAAAA"

  26. 21

    80

    Returns: "AAAAAAABBBBBBBBABBBAA"

  27. 22

    69

    Returns: "AAAAAABBBBBBBBABBBAAAA"

  28. 23

    36

    Returns: "AAABBBBBBBBBBBBAAAAAAAA"

  29. 24

    102

    Returns: "AAAAAAAABBBBBBABBBBBBAAA"

  30. 25

    242

    Returns: ""

  31. 26

    122

    Returns: "AAAAAAAAABBBBBBBBABBBBBAAA"

  32. 27

    85

    Returns: "AAAAAABBBBBBBBBBBBBABAAAAAA"

  33. 28

    20

    Returns: "ABBBBBBBBABBBBBBAAAAAAAAAAAA"

  34. 29

    22

    Returns: "ABBBBBBBBABBBBBBBAAAAAAAAAAAA"

  35. 30

    273

    Returns: ""

  36. 31

    146

    Returns: "AAAAAAAAABBBBBBBBBBBBBBABBAAAAA"

  37. 32

    213

    Returns: "AAAAAAAAAAAAABBBBBBBBBBBABBBBBAA"

  38. 33

    155

    Returns: "AAAAAAAAABBBBBBBBBBBBBBBABBAAAAAA"

  39. 34

    458

    Returns: ""

  40. 35

    481

    Returns: ""

  41. 36

    452

    Returns: ""

  42. 37

    288

    Returns: "AAAAAAAAAAAAAAABBBBBBBBBBBBBBBBABBBAA"

  43. 38

    332

    Returns: "AAAAAAAAAAAAAAAAABBBBBBBBBBABBBBBBBBBA"

  44. 39

    58

    Returns: "AABBABBBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAAA"

  45. 40

    240

    Returns: "AAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBAAAAAAAA"

  46. 41

    218

    Returns: "AAAAAAAAAABBBBBBBBBBBBBABBBBBBBBAAAAAAAAA"

  47. 42

    186

    Returns: "AAAAAAAABBBABBBBBBBBBBBBBBBBBBAAAAAAAAAAAA"

  48. 43

    207

    Returns: "AAAAAAAAABBBBBBBBBBBBBABBBBBBBBBAAAAAAAAAAA"

  49. 44

    266

    Returns: "AAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBABBAAAAAAAAA"

  50. 45

    169

    Returns: "AAAAAAABBBBBBBBBBBBBBBABBBBBBBBAAAAAAAAAAAAAA"

  51. 46

    377

    Returns: "AAAAAAAAAAAAAAAABBBBBBBBBBBBBBABBBBBBBBBAAAAAA"

  52. 47

    774

    Returns: ""

  53. 48

    359

    Returns: "AAAAAAAAAAAAAABABBBBBBBBBBBBBBBBBBBBBBBAAAAAAAAA"

  54. 49

    97

    Returns: "AAABBBABBBBBBBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAAAAAAA"

  55. 50

    590

    Returns: "AAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBABBBBBBBBBBBBBBBA"

  56. 49

    600

    Returns: "AAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBB"

  57. 49

    601

    Returns: ""

  58. 50

    625

    Returns: "AAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBB"

  59. 50

    626

    Returns: ""

  60. 50

    1225

    Returns: ""

  61. 7

    11

    Returns: "AABABBB"

  62. 9

    17

    Returns: "AAABBBABB"

  63. 50

    401

    Returns: "AAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBABAAAAAAAA"

  64. 35

    219

    Returns: "AAAAAAAAAAAABBBBBBBBBBBBBBBABBBAAAA"

  65. 50

    117

    Returns: "AAAABBBBBBBBABBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAAAAAAA"

  66. 12

    13

    Returns: "AABBBBBABAAA"

  67. 5

    5

    Returns: "ABABB"

  68. 6

    7

    Returns: "AABBAB"

  69. 8

    11

    Returns: "AABABBBA"

  70. 50

    599

    Returns: "AAAAAAAAAAAAAAAAAAAAAAABABBBBBBBBBBBBBBBBBBBBBBBBA"

  71. 50

    623

    Returns: "AAAAAAAAAAAAAAAAAAAAAAAABBABBBBBBBBBBBBBBBBBBBBBBB"

  72. 50

    67

    Returns: "AABBBBBBBBABBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAAAAAAAAA"

  73. 10

    0

    Returns: "BBBBBAAAAA"

  74. 5

    7

    Returns: ""

  75. 10

    1

    Returns: "BBBBABAAAA"

  76. 49

    599

    Returns: "AAAAAAAAAAAAAAAAAAAAAAABABBBBBBBBBBBBBBBBBBBBBBBB"

  77. 10

    11

    Returns: "AABBBBABAA"

  78. 10

    13

    Returns: "AABBABBBAA"

  79. 7

    7

    Returns: "ABABBBA"

  80. 50

    1220

    Returns: ""

  81. 5

    1

    Returns: "BBABA"

  82. 12

    26

    Returns: "AAAABBBBABBA"

  83. 50

    565

    Returns: "AAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBABBBBBBBBBBBBBBBAA"

  84. 40

    10

    Returns: "BBBBBBBBBBABBBBBBBBBBAAAAAAAAAAAAAAAAAAA"

  85. 50

    501

    Returns: "AAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBABAAAA"

  86. 50

    636

    Returns: ""

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