Class Solution
java.lang.Object
g1201_1300.s1220_count_vowels_permutation.Solution
public class Solution
extends java.lang.Object
1220 - Count Vowels Permutation.
Hard
Given an integer n
, your task is to count how many strings of length n
can be formed under the following rules:
- Each character is a lower case vowel (
'a'
,'e'
,'i'
,'o'
,'u'
) - Each vowel
'a'
may only be followed by an'e'
. - Each vowel
'e'
may only be followed by an'a'
or an'i'
. - Each vowel
'i'
may not be followed by another'i'
. - Each vowel
'o'
may only be followed by an'i'
or a'u'
. - Each vowel
'u'
may only be followed by an'a'.
Since the answer may be too large, return it modulo 10^9 + 7.
Example 1:
Input: n = 1
Output: 5
Explanation: All possible strings are: “a”, “e”, “i” , “o” and “u”.
Example 2:
Input: n = 2
Output: 10
Explanation: All possible strings are: “ae”, “ea”, “ei”, “ia”, “ie”, “io”, “iu”, “oi”, “ou” and “ua”.
Example 3:
Input: n = 5
Output: 68
Constraints:
1 <= n <= 2 * 10^4
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Constructor Summary
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Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Constructor Details
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Solution
public Solution()
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Method Details
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countVowelPermutation
public int countVowelPermutation(int n)
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