ufchecker_2.fs

    let inline isPhom x y z =  
        let sx, sy, sz = x%13,y%13,z%13
        if sx = sy && sy = sz then true
        else
            let tx, ty, tz = x/13, y/13, z/13
            if tx = ty && ty = tz then
                let a = max sx sy |> max sz
                let c = min sx sy |> min sz
                let b = (sx + sy + sz)/3
                a = b + 1 && a = c + 2
            else false        

    let checkUf (cards: int []) = 
        let group = Array.init 10 (fun _ -> 0)

        let loop f =
            let mutable found = false

            for i = 0 to 9-2 do
                if not found && group.[i] = 0 then
                    for j = i+1 to 9-1 do
                        if not found && group.[j] = 0 then
                            for k = j+1 to 9 do
                                if not found && group.[k] = 0 then
                                    found <- f i j k

            found
            
        let mask i j k b = group.[i] <- b; group.[j] <- b; group.[k] <- b

        let rec check i j k depth =
            if isPhom cards.[i] cards.[j] cards.[k] then           
                if depth = 3 then 
                    true
                else
                    mask i j k depth
                    if loop (fun x y z -> check x y z (depth + 1)) then true
                    else
                        mask i j k 0
                        false
            else false
        loop (fun x y z -> check x y z 1), group