A-M baby

Task/Huffman-coding/J/huffman-coding-1.j

@@ -0,0 +1,14 @@
+hc=: 4 : 0
+ if. 1=#x do. y
+ else. ((i{x),+/j{x) hc (i{y),<j{y [ i=. (i.#x) -. j=. 2{./:x end.
+)
+
+hcodes=: 4 : 0
+ assert. x -:&$ y           NB. weights and words have same shape
+ assert. (0<:x) *. 1=#$x    NB. weights are non-negative
+ assert. 1 >: L.y           NB. words are boxed not more than once
+ w=. ,&.> y                 NB. standardized words
+ assert. w -: ~.w           NB. words are unique
+ t=. 0 {:: x hc w           NB. minimal weight binary tree
+ ((< S: 0 t) i. w) { <@(1&=)@; S: 1 {:: t
+)