LeetCode/kt/largest-3-same-digit-number-in-string.kt

class Solution {
    fun largestGoodInteger(num: String): String = num
        .asSequence()
        .windowed(3)
        .filter { s ->
            s[0] == s[1] && s[1] == s[2]
        }
        .map { window ->
            window.joinToString("")
        }
        .maxByOrNull { num ->
            num.toInt()
        } ?: ""
}