June 2018 Update

Task/Move-to-front-algorithm/Ring/move-to-front-algorithm.ring

@@ -0,0 +1,42 @@
+# Project : Move-to-front algorithm
+# Date    : 2018/01/13
+# Author : Gal Zsolt (~ CalmoSoft ~)
+# Email   : <calmosoft@gmail.com>
+
+test("broood")
+test("bananaaa")
+test("hiphophiphop")
+
+func encode(s)
+        symtab = "abcdefghijklmnopqrstuvwxyz"
+        res = ""
+        for i=1 to len(s)
+             ch = s[i]
+             k = substr(symtab, ch)
+             res = res + " " + (k-1)
+             for j=k to 2 step -1
+                  symtab[j] = symtab[j-1]
+             next
+             symtab[1] = ch
+        next
+        return res
+
+func decode(s)
+        s = str2list( substr(s, " ", nl) )
+        symtab = "abcdefghijklmnopqrstuvwxyz"
+        res = ""
+        for i=1 to len(s)
+             k = number(s[i]) + 1
+             ch = symtab[k]
+             res = res + " " + ch
+             for j=k to 2 step -1
+                   symtab[j] = symtab[j-1]
+             next
+             symtab[1] = ch
+        next
+        return right(res, len(res)-2)
+
+func test(s)
+        e = encode(s)
+        d = decode(e)
+        see "" + s + " => " + "(" + right(e, len(e) - 1) + ") " + " => " + substr(d, " ", "") + nl