A-M baby

Task/LZW-compression/J/lzw-compression-1.j

@@ -0,0 +1,14 @@
+encodeLZW =: 4 : 0
+ d=. ;/x
+ r=.0$0
+ wc=.w=.{.y
+ for_c. }.y do.
+   wc=.w,c
+   if. d e.~ <wc do. w=.wc else.
+     r=. r, d i.<w
+     d=.d,<wc
+     w=.c
+   end.
+ end.
+ r, d i.<w
+)

Task/LZW-compression/J/lzw-compression-2.j

@@ -0,0 +1,16 @@
+decodeLZW =: 4 : 0
+ d=.;/x
+ w=.r=. >d{~{.y
+ ds=. #d
+ for_c. }.y do.
+   select. * c-ds
+    case. _1 do. r=.r,e=.>c{d
+    case.  0 do. r=.r,e=.w,{.w
+    case.    do. 'error' return.
+   end.
+   d=.d,< w,{.e
+   w=.e
+   ds=.ds+1
+ end.
+ ;r
+)