Scala 936
type O=Option[(Char,Int)]
type Q=(O,O)
type L=List[Q]
val N=None
def t(a:Int,b:Int):Q=if(a>b)(Some('-',a-b),(if(b!=0&&b*(a/b)==a)Some('/',a/b)else N))else
(Some('+',b-a),(if(a!=0&&a*(b/a)==b)Some('*',b/a)else N))
def w(a:Q,b:Q)=if(a._1==b._1&&a._2==b._2)a else
if(a._1==b._1)(a._1,N)else
if(a._2==b._2)(N,a._2)else(N,N)
def n(l:L):Q=l match{case Nil=>(N,N)
case x::Nil=>x
case x::y::Nil=>w(x,y)
case x::y::xs=>n(w(x,y)::xs)}
def z(l:L,w:Int)=for(d<-1 to w)yield
n(l.drop(d-1).sliding(1,w).flatten.toList)
def h(s:L):Boolean=s.isEmpty||(s(0)!=(N,N))&& h(s.tail)
def j(s:L,i:Int=1):Int=if(h(z(s,i).toList))i else j(s,i+1)
def k(b:Int,o:Char,p:Int)=o match{case'+'=>b+p
case'-'=>b-p
case'*'=>b*p
case _=>b/p}
val e=getLine
val i=e.split(" ").map(_.toInt).toList
val s=i.sliding(2,1).toList.map(l=>t(l(0),l(1)))
val H=n(s.drop(s.size%j(s)).sliding(1,j(s)).flatten.toList)
val c=H._1.getOrElse(H._2.get)
println (k(i(i.size-1),c._1,c._2))
ungolfed:
type O = Option[(Char, Int)]
def stepalize (a: Int, b: Int): (O, O) = (a > b) match {
case true => (Some('-', a-b), (if (b!=0 && b * (a/b) == a) Some ('/', a/b) else None))
case false=> (Some('+', b-a), (if (a!=0 && a * (b/a) == b) Some ('*', b/a) else None)) }
def same (a: (O, O), b: (O, O)) = {
if (a._1 == b._1 && a._2 == b._2) a else
if (a._1 == b._1) (a._1, None) else
if (a._2 == b._2) (None, a._2) else
(None, None)}
def intersection (lc: List[(O, O)]): (O, O) = lc match {
case Nil => (None, None)
case x :: Nil => x
case x :: y :: Nil => same (x, y)
case x :: y :: xs => intersection (same (x, y) :: xs)}
def seriallen (lc: List[(O, O)], w: Int= 1) =
for (d <- 1 to w) yield
intersection (lc.drop (d-1).sliding (1, w).flatten.toList)
def hit (s: List[(O, O)]) : Boolean = s match {
case Nil => true
case x :: xs => (x != (None, None)) && hit (xs)}
def idxHit (s: List[(O, O)], idx: Int = 1) : Int =
if (hit (seriallen (s, idx).toList)) idx else
idxHit (s, idx+1)
def calc (base: Int, op: Char, param: Int) = op match {
case '+' => base + param
case '-' => base - param
case '*' => base * param
case _ => base / param}
def getOp (e: String) = {
val i = e.split (" ").map (_.toInt).toList
val s = i.sliding (2, 1).toList.map (l => stepalize (l(0), l(1)))
val w = idxHit (s)
val hit = intersection (s.drop (s.size % w).sliding (1, w).flatten.toList)
val ci = hit._1.getOrElse (hit._2.get)
val base = i(i.size - 1)
println ("i: " + i + " w: " + w + " ci:" + ci + " " + calc (base, ci._1, ci._2))
}
val a="1 3 5 7 9 11"
val b="1 3 2 4 3 5 4 6 5 7 6"
val c="2 6 7 3 9 10 6 18 19 15 45 46"
val d="1024 512 256 128 64 32 16"
val e="1 3 9 8 24 72 71 213 639"
val f="1 2 3 4 5 2 3 4 5 6 3 4 5 6 7"
val g="1 2 4 1 3 9 5 8 32 27 28 56 53 55 165 161 164 656 651 652 1304"
val h="0 0 1 2 3 6 7 14"
val i="0 0 0 0 1 0 0 0 0 1 0"
List (a, b, c, d, e, f, g, h, i).map (getOp)
Fails miserably on Peter Taylor's h, but I don't see the possibility to heal the program in a reasonable amount of time.
