June 2018 Update

Task/Josephus-problem/PicoLisp/josephus-problem.l

@@ -0,0 +1,23 @@
+#general solution
+(de jo (N K)
+   (if (=1 N)
+      1
+      (inc
+         (%
+            (+ (dec K) (jo (dec N) K))
+            N ) ) ) )
+
+#special case when K is 2; much faster than general version.
+(de jo2(N)
+   (let P 1
+      (while (<= P N)
+         (setq P (* 2 P))
+         (+ (- (* 2 N) P) 1) ) ) )
+
+# find the survivor using an optimal solution
+(de survivor (N K)
+   (if (=0 (% N 2))
+      (jo2 N)
+      (jo N K) ) )
+(print (survivor 5 2))
+(print (survivor 41 3))