Statistics

Problem Statement for "ThreeProgrammers"

Problem Statement

This problem is about three programmers who work together on a project. The programmers' names are Alice, Bob, and Charles. We will use 'A', 'B', and 'C' to denote them.

Each day exactly one of the three programmers works on the project. The code history is a string that specifies who worked on which day. For example, the string "AAC" means that Alice worked on the project for two days in a row and then Charles worked for a day.

Alice is always able to work on the project. Each time Bob spends a day working, he needs to take at least one day off before he is able to work again. Each time Charles spends a day working, he needs to take at least two days off.

The above information means that not all strings are valid code histories. For example, the string "BB" is not a valid code history because Bob cannot work two days in a row.

You are given a String code. This may or may not be a valid code history. Find any permutation of letters of code that produces a valid code history, and return that code history. If there are multiple solutions, you may return any of them. If there are no solutions, return "impossible" instead.

Definition

Class:
ThreeProgrammers
Method:
validCodeHistory
Parameters:
String
Returns:
String
Method signature:
String validCodeHistory(String code)
(be sure your method is public)

Constraints

  • code will contain between 1 and 50 characters, inclusive.
  • Each character in code will be one of 'A', 'B', and 'C'.

Examples

  1. "CAB"

    Returns: "BCA"

    The input is a valid code history. In fact, any permutation of this input is a valid code history, and you may return any of them.

  2. "CBB"

    Returns: "BCB"

    Bob cannot work on two consecutive days. Hence, "BCB" is the only valid code history that is a permutation of the given input.

  3. "BB"

    Returns: "impossible"

  4. "BBA"

    Returns: "BAB"

  5. "CAC"

    Returns: "impossible"

  6. "ACAC"

    Returns: "CAAC"

  7. "ACABC"

    Returns: "ACABC"

  8. "BAABCABBCCACBAACABAABABBCCAACABCCAACCABCACACCBABAB"

    Returns: "BACBABCAACBACABCBACBACABCBACBACABCABCAACBACAACABCA"

  9. "C"

    Returns: "C"

  10. "CC"

    Returns: "impossible"

  11. "CCC"

    Returns: "impossible"

  12. "B"

    Returns: "B"

  13. "CB"

    Returns: "BC"

  14. "CBC"

    Returns: "impossible"

  15. "CCBC"

    Returns: "impossible"

  16. "BB"

    Returns: "impossible"

  17. "CBB"

    Returns: "BCB"

  18. "CBCB"

    Returns: "impossible"

  19. "CCBCB"

    Returns: "impossible"

  20. "BBB"

    Returns: "impossible"

  21. "BBCB"

    Returns: "impossible"

  22. "CBBBC"

    Returns: "impossible"

  23. "BCCBCB"

    Returns: "impossible"

  24. "A"

    Returns: "A"

  25. "CA"

    Returns: "CA"

  26. "CCA"

    Returns: "impossible"

  27. "CACC"

    Returns: "impossible"

  28. "BA"

    Returns: "BA"

  29. "BCA"

    Returns: "BCA"

  30. "BCAC"

    Returns: "CBAC"

  31. "CACBC"

    Returns: "impossible"

  32. "BBA"

    Returns: "BAB"

  33. "CBAB"

    Returns: "BCBA"

  34. "BCBAC"

    Returns: "CBABC"

  35. "CACCBB"

    Returns: "impossible"

  36. "BBAB"

    Returns: "impossible"

  37. "CBABB"

    Returns: "BCBAB"

  38. "BBACCB"

    Returns: "BCBABC"

  39. "CBBCACB"

    Returns: "impossible"

  40. "AA"

    Returns: "AA"

  41. "CAA"

    Returns: "CAA"

  42. "ACCA"

    Returns: "CAAC"

  43. "CACCA"

    Returns: "impossible"

  44. "BAA"

    Returns: "BAA"

  45. "CBAA"

    Returns: "BCAA"

  46. "CCAAB"

    Returns: "CBACA"

  47. "CCCAAB"

    Returns: "impossible"

  48. "BBAA"

    Returns: "BABA"

  49. "ACBAB"

    Returns: "BCBAA"

  50. "ACABCB"

    Returns: "CBABCA"

  51. "CCBCABA"

    Returns: "CBACBAC"

  52. "BBABA"

    Returns: "BABAB"

  53. "BBABCA"

    Returns: "BCBABA"

  54. "BCABCBA"

    Returns: "BCBABCA"

  55. "BCCCABBA"

    Returns: "CBABCBAC"

  56. "AAA"

    Returns: "AAA"

  57. "AACA"

    Returns: "CAAA"

  58. "CACAA"

    Returns: "CAACA"

  59. "CCAAAC"

    Returns: "impossible"

  60. "ABAA"

    Returns: "BAAA"

  61. "CBAAA"

    Returns: "BCAAA"

  62. "CCAABA"

    Returns: "CBACAA"

  63. "CCACBAA"

    Returns: "CBACAAC"

  64. "ABABA"

    Returns: "BABAA"

  65. "BCBAAA"

    Returns: "BCBAAA"

  66. "BABACAC"

    Returns: "CBABCAA"

  67. "ACABCACB"

    Returns: "CBACBACA"

  68. "BABAAB"

    Returns: "BABABA"

  69. "BBABCAA"

    Returns: "BCBABAA"

  70. "BAACCABB"

    Returns: "BCBABCAA"

  71. "CBBAACCBA"

    Returns: "CBABCBACA"

  72. "CAAAAABAACAABBCBCCBABACBBAACCBBBCCBCCBBCACC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  73. "ACBCBAACCBCCCBBACBACAAACBABACABABBABCCCCBACB"

    Returns: "impossible"

  74. "AACACCBCBBACBCBCBCAACBBCAAAAABACBBCACCCBACCBB"

    Returns: "impossible"

  75. "CCABAACABACCBBCCABBCCBACCABBCBAABABBBAACCBA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACA"

  76. "CCACCACABAABABBBBBAACCCCABBCBCAABCBBBCBAACAC"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  77. "BCAACBCBBCCBBBCACABCACCAACBAAABBBACACCCABCBBA"

    Returns: "impossible"

  78. "ABBBCBACCCCCCBBCAABBACBABCAACABBBACBCCBCACAACA"

    Returns: "impossible"

  79. "CACACCACAABBAAABBCBCBBBAABACBBCBCACBCBBAACCB"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACA"

  80. "ABCBCBBACBAAAAABACBABBBCBCABCBABCACCCCCACCBAB"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBAC"

  81. "BBABBCCBABCAACCABCCACCABABBBCABBBBCBCACCACAAAC"

    Returns: "impossible"

  82. "ABCCAAAABCAACBCCCBACBBAAABBCBBCCCCCAABCCABBBCBB"

    Returns: "impossible"

  83. "CBCACBBCABBCBCABBBAACBACCBBABABCACBCABAAACBAC"

    Returns: "CBABCBABCBABCBABCBACBACBACBACBACBACBACBACBACA"

  84. "ACABAABCCBCBAAABCCBCCABACBACBBACBACABBBACCCBBB"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACBAC"

  85. "BBCABBABBBACBBBBCCCBBAABCCCCBCCCAACAAAAAAABCCBC"

    Returns: "impossible"

  86. "BABBACAABCBBBCACCABAACABBBCBACCCAABCBCBCCBCAACCB"

    Returns: "impossible"

  87. "ABBBABCCBCCACACCACAACCBBABAAAABBBAACBBCCACB"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACAA"

  88. "ABABCBBCAABACBCACCCABCAACCBCBCAABCABACCBBABA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  89. "CCAAABBABBABCBACBABCCBCACACAACCABCCCCCAABABBB"

    Returns: "impossible"

  90. "CCCCABAAACAABCABABCBCBAAABCBBCCBCCCCBCBCBAAABA"

    Returns: "impossible"

  91. "ABBBACBAAACCACBAAABBACCBCBBABBCCAAACCCCBABCB"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACAA"

  92. "BBABCABBCABACCCAACCCACACBBCBBBBAACCCBACBABAAA"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  93. "AACAACCBABCCCABBBACCCABCACAABBBBCBBAACBCBCACAB"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  94. "BCCCBBAAACAACCACCABCBCABCACAABBABBABCACBCBACBBC"

    Returns: "impossible"

  95. "CABACACCCACBBACBBBACABAABACCBBBBACCAACBBBCABA"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACAA"

  96. "BABCAAAAAACCCCABBBBCBBACCBBABCCBABAAABBCCCCACB"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACA"

  97. "ABBBABBABACBACACACBACCCABBBCCABCACBBBCAACACCCAB"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  98. "CCCACBCABCCCBBCACBBACACCBCABBBCABAAACABBBAAABABC"

    Returns: "impossible"

  99. "CAABBCBACBBCCBACBCACBCBCABBACBCACBBBCABABAAAAA"

    Returns: "CBABCBABCBABCBABCBACBACBACBACBACBACBACBACBACAA"

  100. "CCCCBCCBABBBCBBAABACBBCBBAAACACABACABCABAAACBCB"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACBACA"

  101. "CBACCCBACCCBABCCBACABBABCACBCBBBABAAAABABCBBACAC"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  102. "BACCBABABBBBBBAABAACBCBABAACCCCCACCBBCACACCCCAABB"

    Returns: "impossible"

  103. "ACBABCACBCBAABCCBBACCBCBAABBACABACCCAABAACBA"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACAAA"

  104. "BACCBBAAAACABBACAAABBCBBCAACBBBCCACBAAABCCCCC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACAA"

  105. "ABCBABCABACCAACABCCBACBCBABBAACCCBACCAACBAABCB"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACAAC"

  106. "ACACACACBCACACBBBBAAAABBACCCAACCBCBBCABCBACCBAB"

    Returns: "impossible"

  107. "BCBBABAACAACBBBACBBABCCACCAABCABBAABACCCACBCA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACAAA"

  108. "BCACABBABCABAABCCBBBCABCCACAAACABCBACBCBCABCAA"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACAA"

  109. "ABACBBBBCCCBBCCCAACCACBCBBAACBCBAACCAAAABACBBAA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  110. "BCBBCAACCBABAACCBCCBAAACACCABBBBCAAACCAACBBBACCB"

    Returns: "impossible"

  111. "AABBBCCBCCBABACCAAACCBBBBAAACCCBBCABAABABACBAC"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACAAA"

  112. "BAAABACCBBACCCCACACACAABBCBBCCBBCABABABACBBAACB"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACAA"

  113. "AABCBABAACCCCAABBCCABBACBBCCBCBABBAAABCCBBCAAACC"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  114. "CBBABAAACCCCCACBACABAACBCBABBCCBABBBAABABCCCCABAC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  115. "BBAACACBCABCABABAACCABACBCBCBBCAABACABBCBBCCABA"

    Returns: "CBABCBABCBABCBABCBACBACBACBACBACBACBACBACBACAAA"

  116. "BCBBAACCBAABCCBACAABBCACBCCACCCBBAAABBBCBABACABA"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACBACAA"

  117. "AABCCABBBCBCCACCCBAACBABBAACBCAABAAACABCABBCCBBBC"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  118. "AAABAABCAABABBCCCACACBBCAACBCBBCCCACCBBCBAACBCBABB"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  119. "ABBABBABACABCACACABACABAABBACCAABBCCBBACCCCCA"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACAAAA"

  120. "BBABAACBABBCABBACCAABCABBBABCCAACACCCBCCAAACCA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACAAA"

  121. "CAACBABBBAAAAAABCBCABCCBABCCBCAACCACACBBBABCACC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACAACA"

  122. "BBCAAACACCACCAAACCABCBCACCBBAAABBCABCBBACCBABACB"

    Returns: "impossible"

  123. "BBBCCACACBABACACACABBCAABCCBBABBCCBAABCBACAAAA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACAAAA"

  124. "CBCCCACCBAABCABAACCBABABAABAACCBBCCBAAABABCCBAB"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACAAA"

  125. "BBBCACCCBCABABABBABCCABCBCACCBCCCCAAABAABABAAACA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACAA"

  126. "CAACCCBABAABCCBCCBAACBBCCCBABACBBACACAAAABACBBBCA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACAAC"

  127. "BBBCAABACCBBBACBCCACACBCBBCACABAAABABAACCCBBAAA"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACAAAA"

  128. "ABAACCCCBBBAACCBBBCBCCABAAACBACCBBBCAABABACCABAA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACAAA"

  129. "BBCBBBCACABCACCBCABBCBAAABAACAAABBBCCCCACCAABBACA"

    Returns: "CBABCBACBACBACBACBACBACBACBACBACBACBACBACBACBACAA"

  130. "CBBACBAACCACCCBCCBCCBAAABBCCCACCAABAABCBBBABAAAABB"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACA"

  131. "BABBCBACACABBCBAAAAACCCBBABBACCACCBBACAAAACBCBBB"

    Returns: "CBABCBABCBABCBABCBACBACBACBACBACBACBACBACBACAAAA"

  132. "BAAAABBACABACCCABBBBAABACCAAABBCCBBCAABCBCCBCCACB"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACBACAAA"

  133. "BCCCBCCBABBACABABAAABBACBCCCAACCBACBBCBABACAABCABA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACBACAA"

  134. "BABBABABBABABBBAAABAAAABBAAAAABBABBBABBBBAAABAA"

    Returns: "BABABABABABABABABABABABABABABABABABABABABABABAA"

  135. "BAAABABBBAAAABABAAABAAABABBBAAABBBBABBBBAABBBBAA"

    Returns: "BABABABABABABABABABABABABABABABABABABABABABABABA"

  136. "ABAABABABBBBABBABAABABBAAABBABBBBBBAABBABBAABAAAAA"

    Returns: "impossible"

  137. "CBCBBCCBBAABAABBCABABCBBCCCCCAAABBABCBBBBBABB"

    Returns: "CBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

  138. "ABBACCCBBCCCBBBCABABBAAABBCBCAABBCCABBBBBBBBCA"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

  139. "CBAAABBABBBBBABCACCBBAABCBBBACBBCCCBBBBBBCAACCB"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCB"

  140. "BABCBBBBCABAAACABBBCBBBCCCCBCACBBBAABABABBCCBBBB"

    Returns: "impossible"

  141. "AABBBBBBCCC"

    Returns: "BCBABCBABCB"

  142. "BBBACCB"

    Returns: "BCBABCB"

  143. "BABBCCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABABBA"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABABAB"

  144. "AAABBBBBCCCC"

    Returns: "CBABCBABCBAC"

  145. "AAACCCCBBBBBBBB"

    Returns: "BCBABCBABCBABCB"

  146. "BCBABCBABCBABCB"

    Returns: "BCBABCBABCBABCB"

  147. "BCBCBABAB"

    Returns: "BCBABCBAB"

  148. "BBBBACC"

    Returns: "BCBABCB"

  149. "CAAC"

    Returns: "CAAC"

  150. "ABBBBCC"

    Returns: "BCBABCB"

  151. "AAABBBCCCC"

    Returns: "CBACBACBAC"

  152. "CCBBB"

    Returns: "impossible"

  153. "BBBCC"

    Returns: "impossible"

  154. "BAB"

    Returns: "BAB"

  155. "BABCBABCB"

    Returns: "BCBABCBAB"

  156. "BBBBCCA"

    Returns: "BCBABCB"

  157. "BCBABCBABCB"

    Returns: "BCBABCBABCB"

  158. "BCBABCB"

    Returns: "BCBABCB"

  159. "CBBABBAAACBBAAACCBBCAABCBCABBABBBBBACBBBBCBCBBBCCC"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

  160. "BBC"

    Returns: "BCB"

  161. "BABB"

    Returns: "impossible"

  162. "BCCA"

    Returns: "CBAC"

  163. "AAABBBBBBCCCC"

    Returns: "CBABCBABCBABC"

  164. "ABCBABCACBABCBABCACBABCBABCACBABCBABCACBABCBABCACB"

    Returns: "CBABCBABCBABCBABCBABCBABCBACBACBACBACBACBACBACBACA"

  165. "CCCCCCCCCCCCCCCCCBBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAA"

    Returns: "impossible"

  166. "BCCBCCBBCCCCBCACCBCCBCBBCCACCCBCCCCACCBCCCCCCBCBCB"

    Returns: "impossible"

  167. "BBBCA"

    Returns: "BCBAB"

  168. "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

  169. "BCBABCBA"

    Returns: "BCBABCBA"

  170. "CBBCBAC"

    Returns: "impossible"

  171. "CBAC"

    Returns: "CBAC"

  172. "BCBABCBABCBAB"

    Returns: "BCBABCBABCBAB"

  173. "CCCCCCCCCCCCCCCCBBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAA"

    Returns: "CBABCBABCBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  174. "BCBAB"

    Returns: "BCBAB"

  175. "CCBBBA"

    Returns: "BCBABC"

  176. "ABBBC"

    Returns: "BCBAB"

  177. "CCCCBBBBAAAB"

    Returns: "CBABCBABCBAC"

  178. "AAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCC"

    Returns: "impossible"

  179. "AABBBBBCCC"

    Returns: "BCBABCBABC"

  180. "CBCA"

    Returns: "CBAC"

  181. "CCCCCCCCCCCCCCCCCBBBBBBBBBBBBBBBBAAAAAAAAAAAAAAAA"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  182. "CBABCB"

    Returns: "BCBABC"

  183. "CCCCCCCCBBBBBBBBBBBAAAAAAA"

    Returns: "CBABCBABCBABCBABCBACBACBAC"

  184. "CBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCB"

    Returns: "BCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABCBABC"

  185. "ABCACBABCCABBBCAACCBAACBABBCCBBBBBCBCBCBAACCAABBBA"

    Returns: "CBABCBABCBABCBABCBABCBABCBABCBACBACBACBACBACBACBAC"

  186. "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  187. "BCBABCBAB"

    Returns: "BCBABCBAB"

  188. "ABCABCABCABCABCABCABCABCABCABCABCABCABCABCABCABCC"

    Returns: "CBACBACBACBACBACBACBACBACBACBACBACBACBACBACBACBAC"

  189. "BABACCBABBAAABCCBBCBBACAACBBABBBBCCACACC"

    Returns: "CBABCBABCBABCBABCBABCBACBACBACBACBACBACA"

  190. "ABCABCABCABCABCABCABCABCABCABCABCABCABCABCABCACC"

    Returns: "impossible"

  191. "BBCC"

    Returns: "impossible"

  192. "BCBACBABBC"

    Returns: "BCBABCBABC"

  193. "BCBC"

    Returns: "impossible"

  194. "BCBABCBABCBABCBABCBABCB"

    Returns: "BCBABCBABCBABCBABCBABCB"

  195. "CBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCBCB"

    Returns: "impossible"

  196. "CBBCAB"

    Returns: "BCBABC"

  197. "BBBBBBBBCCCCAAA"

    Returns: "BCBABCBABCBABCB"

  198. "BBBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCAAAAAAAAAAAAAAAAA"

    Returns: "CBABCBABCBABCBACBACBACBACBACBACBACBACBACBACBACAAA"

  199. "CCCCCCBBBBBBBAAAAA"

    Returns: "CBABCBABCBACBACBAC"

  200. "BBBBBBBBBBBBBAAAAAACCCCCC"

    Returns: "BCBABCBABCBABCBABCBABCBAB"

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