tasks a-s

Task/Run-length-encoding/Pure/run-length-encoding.pure

@@ -0,0 +1,15 @@
+using system;
+
+encode s = strcat $ map (sprintf "%d%s") $ encode $ chars s with
+  encode [] = [];
+  encode xs@(x:_) = (#takewhile (==x) xs,x) : encode (dropwhile (==x) xs);
+end;
+
+decode s = strcat [c | n,c = parse s; i = 1..n] with
+  parse s::string = regexg item "([0-9]+)(.)" REG_EXTENDED s 0;
+  item info = val (reg 1 info!1), reg 2 info!1;
+end;
+
+let s = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW";
+let r = encode s; // "12W1B12W3B24W1B14W"
+decode r;