릿코드 2147. Number of Ways to Divide a Long Corridor 코틀린

의자카운트랑 마지막의자인덱스 저장해두고,의자카운트가 2배수면 정답에 인덱스-마지막의자인덱스 추가


정답

class Solution {
    fun numberOfWays(corridor: String): Int {
        val MOD = 1000000007
        val SEAT = 'S'
        val PLANT = 'P'
        var seatCount = 0
        var ans = 1L
        var lastSeatIndex = -1
        for ((index, ch) in corridor.withIndex()) {
            if (ch == SEAT) {
                seatCount++
                if (seatCount > 1 && seatCount % 2 != 0) {
                    ans = (ans * (index - lastSeatIndex)) % MOD
                }
                lastSeatIndex = index
            }
        }
        return if (seatCount < 2 || seatCount % 2 != 0) 0 else maxOf(ans  % MOD , 1L).toInt()
    }
}