1415. The k-th Lexicographical String of All Happy Strings of Length n
Description
A happy string is a string that:
- consists only of letters of the set
['a', 'b', 'c']
. s[i] != s[i + 1]
for all values ofi
from1
tos.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.
Given 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
.
Example 1:
Input: n = 1, k = 3 Output: "c" Explanation: The list ["a", "b", "c"] contains all happy strings of length 1. The third string is "c".
Example 2:
Input: n = 1, k = 4 Output: "" Explanation: There are only 3 happy strings of length 1.
Example 3:
Input: n = 3, k = 9 Output: "cab" Explanation: 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"
Constraints:
1 <= n <= 10
1 <= k <= 100
Solutions
Solution 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
|