LeetCode Entry

2264. Largest 3-Same-Digit Number in String

04.12.2023 easy 2023 kotlin

Largest 3-same-digit number in a string

2264. Largest 3-Same-Digit Number in String easy blog post substack youtube

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Problem TLDR

Largest 3-same-digit number in a string

Intuition

There are totally 10 such numbers: 000, 111, ..., 999.

Approach

Let’s use Kotlin’s API

windowed
filter
maxByOrNull

Complexity

Time complexity: \(O(n)\)
Space complexity: \(O(n)\), can be O(1) with asSequence()

Code

    fun largestGoodInteger(num: String): String =
      num.windowed(3)
      .filter { it[0] == it[1] && it[0] == it[2] }
      .maxByOrNull { it[0] } ?: ""