7 13.11

import java.io.File

private infix fun Boolean.arrow(other: Boolean) = !(this && !other)

private val invalid = 0 to 1e9.toInt() // max / min

private fun dfs(
    tab: List<List<Int>> = (0..14).map { readLine()!!.trim().split("\t").map(String::toInt) },
    n: Int = 0,
    m: Int = 0,
    dp: List<MutableList<Pair<Int, Int>>> = List(tab.size) { MutableList(tab.first().size) { invalid } }.also { list ->
        list[tab.size - 1][tab.size - 1] = tab[tab.size - 1][tab.size - 1] to tab[tab.size - 1][tab.size - 1]
    }
): Pair<Int, Int> {
    val bool1 = n >= tab.size
    val bool2 = m >= tab.size

    if (bool1 || bool2)
        return invalid

    if (dp[n][m] != invalid)
        return dp[n][m]

    dp[n][m] = run {
        val f = dfs(tab, n + 1, m, dp).takeIf { it != invalid }?.let { (f, s) ->
            when {
                tab[n + 1][m] > tab[n][m] -> (f - tab[n][m]) to (s - tab[n][m])
                else -> (f + tab[n][m]) to (s + tab[n][m])
            }
        } ?: invalid

        val s = dfs(tab, n, m + 1, dp).takeIf { it != invalid }?.let { (f, s) ->
            when {
                tab[n][m + 1] > tab[n][m] -> (f - tab[n][m]) to (s - tab[n][m])
                else -> (f + tab[n][m]) to (s + tab[n][m])
            }
        } ?: invalid

        arrayOf(f.first, s.first).maxOrNull()!! to arrayOf(f.second, s.second).minOrNull()!!
    }

    return dp[n][m]
}

private inline val Iterable<String>.concated
    get() = reduce { acc, s -> "$acc$s" }

fun main() = print(
    File("24-s1.txt")
        .readLines()
        .concated
        .split("A[A-Z]R".toRegex())
        .size - 1
)