A happy string is a string that:
\n\n['a', 'b', 'c'].s[i] != s[i + 1] for all values of i from 1 to s.length - 1 (string is 1-indexed).For example, strings "abc", "ac", "b" and "abcbabcbcb" are all happy strings and strings "aa", "baa" and "ababbc" are not happy strings.
\n\nGiven two integers n and k, consider a list of all happy strings of length n sorted in lexicographical order.
Return the kth string of this list or return an empty string if there are less than k happy strings of length n.
\n
Example 1:
\n\n\nInput: n = 1, k = 3\nOutput: "c"\nExplanation: The list ["a", "b", "c"] contains all happy strings of length 1. The third string is "c".\n\n\n
Example 2:
\n\n\nInput: n = 1, k = 4\nOutput: ""\nExplanation: There are only 3 happy strings of length 1.\n\n\n
Example 3:
\n\n\nInput: n = 3, k = 9\nOutput: "cab"\nExplanation: There are 12 different happy string of length 3 ["aba", "abc", "aca", "acb", "bab", "bac", "bca", "bcb", "cab", "cac", "cba", "cbc"]. You will find the 9th string = "cab"\n\n\n
\n
Constraints:
\n\n1 <= n <= 101 <= k <= 100Compiled with clang 11 using the latest C++ 17 standard.
Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms
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