g1401_1500.s1415_the_k_th_lexicographical_string_of_all_happy_strings_of_length_n

Class Solution

java.lang.Object

g1401_1500.s1415_the_k_th_lexicographical_string_of_all_happy_strings_of_length_n.Solution

public class Solution
extends Object

1415 - The k-th Lexicographical String of All Happy Strings of Length n.

Medium

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 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.

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 9^th string = “cab”

Constraints:

• 1 <= n <= 10
• 1 <= k <= 100

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
String	getHappyString(int n, int k)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

getHappyString

public String getHappyString(int n,
                             int k)