// Airplane seating

(function search [:Array<String> letters min max rowOrColumn]
    (if (= min max)
            min
        (let [middle (Math.floor (/ (+ min max) 2))]
            (case [(letters.shift) rowOrColumn]
                (["F" "row"] (search letters min middle rowOrColumn))
                (["B" "row"] (search letters (+ 1 middle) max rowOrColumn))
                (["L" "column"] (search letters min middle rowOrColumn))
                (["R" "column"] (search letters (+ 1 middle) max rowOrColumn))
                (otherwise (throw "invalid search call"))))))

(function seatId [:String boardingPass]
    (+
        (* 8 (search (.split (boardingPass.substr 0 7) "") 0 127 "row"))
        (search (.split (boardingPass.substr 7) "") 0 7 "column")))