Решение

class Solution {
    fun maxPower(s: String): Int {
        var maxLen = 1
        var currLen = 1
        var currChar = s[0]
        for (i in 1 until s.length) {
            if (s[i] == currChar) {
                currLen++
                maxLen = maxOf(maxLen, currLen)
            } else {
                currChar = s[i]
                currLen = 1
            }
        }
        return maxLen
    }
}