LeetCode in Kotlin
2982. Find Longest Special Substring That Occurs Thrice II
Medium
You are given a string s that consists of lowercase English letters.
A string is called special if it is made up of only a single character. For example, the string "abc" is not special, whereas the strings "ddd", "zz", and "f" are special.
Return the length of the longest special substring of s which occurs at least thrice, or -1 if no special substring occurs at least thrice.
A substring is a contiguous non-empty sequence of characters within a string.
Example 1:
Input: s = “aaaa”
Output: 2
Explanation: The longest special substring which occurs thrice is “aa”: substrings “aaaa”, “aaaa”, and “aaaa”.
It can be shown that the maximum length achievable is 2.
Example 2:
Input: s = “abcdef”
Output: -1
Explanation: There exists no special substring which occurs at least thrice. Hence return -1.
Example 3:
Input: s = “abcaba”
Output: 1
Explanation: The longest special substring which occurs thrice is “a”: substrings “abcaba”, “abcaba”, and “abcaba”.
It can be shown that the maximum length achievable is 1.
Constraints:
3 <= s.length <= 5 * 105sconsists of only lowercase English letters.
Solution
import kotlin.math.max
class Solution {
fun maximumLength(s: String): Int {
val arr = Array(26) { IntArray(4) }
var prev = s[0]
var count = 1
var max = 0
for (index in 1 until s.length) {
if (s[index] != prev) {
val ints = arr[prev.code - 'a'.code]
updateArr(count, ints)
prev = s[index]
count = 1
} else {
count++
}
}
updateArr(count, arr[prev.code - 'a'.code])
for (values in arr) {
if (values[0] != 0) {
max = if (values[1] >= 3) {
max(max, values[0])
} else if (values[1] == 2 || values[2] == values[0] - 1) {
max(max, (values[0] - 1))
} else {
max(max, (values[0] - 2))
}
}
}
return if (max == 0) -1 else max
}
private fun updateArr(count: Int, ints: IntArray) {
if (ints[0] == count) {
ints[1]++
} else if (ints[0] < count) {
ints[3] = ints[1]
ints[2] = ints[0]
ints[0] = count
ints[1] = 1
} else if (ints[2] < count) {
ints[2] = count
ints[3] = 1
}
}
}