2016 Update

Task/Generate-Chess960-starting-position/Scala/generate-chess960-starting-position.scala

@@ -0,0 +1,21 @@
+object Chess960 extends App {
+    private def apply(b: String, e: String) {
+        if (e.length <= 1) {
+            val s = b + e
+            if (is_valid(s)) patterns += s
+        } else
+            for (i <- 0 until e.length)
+                apply(b + e(i), e.substring(0, i) + e.substring(i + 1))
+    }
+
+    private def is_valid(s: String) = {
+        val k = s.indexOf('K')
+        if (k < s.indexOf('R')) false
+        else k < s.lastIndexOf('R') && s.indexOf('B') % 2 != s.lastIndexOf('B') % 2
+    }
+
+    private val patterns = scala.collection.mutable.SortedSet[String]()
+
+    apply("", "KQRRNNBB")
+    for ((s, i) <- patterns.zipWithIndex) println(s"$i: $s")
+}