LeetCode in Kotlin
1641. Count Sorted Vowel Strings
Medium
Given an integer n, return the number of strings of length n that consist only of vowels (a, e, i, o, u) and are lexicographically sorted.
A string s is lexicographically sorted if for all valid i, s[i] is the same as or comes before s[i+1] in the alphabet.
Example 1:
Input: n = 1
Output: 5
Explanation: The 5 sorted strings that consist of vowels only are ["a","e","i","o","u"].
Example 2:
Input: n = 2
Output: 15
Explanation: The 15 sorted strings that consist of vowels only are
[“aa”,”ae”,”ai”,”ao”,”au”,”ee”,”ei”,”eo”,”eu”,”ii”,”io”,”iu”,”oo”,”ou”,”uu”].
Note that “ea” is not a valid string since ‘e’ comes after ‘a’ in the alphabet.
Example 3:
Input: n = 33
Output: 66045
Constraints:
1 <= n <= 50
Solution
class Solution {
fun countVowelStrings(n: Int): Int {
if (n == 1) {
return 5
}
var arr = intArrayOf(1, 1, 1, 1, 1)
var sum = 5
for (i in 2..n) {
val copy = IntArray(5)
for (j in arr.indices) {
if (j == 0) {
copy[j] = sum
} else {
copy[j] = copy[j - 1] - arr[j - 1]
}
}
arr = copy.copyOf(5)
sum = 0
for (k in arr) {
sum += k
}
}
return sum
}
}