funclang series3: implemented challenge.

funclang-taddeus/series3/ass7.ml

@@ -13,13 +13,10 @@ let heads l = map hd l;;
 
 (* 3 *)
 let zip l m =
-    let rec cut l e =
-        let len = (length l) in
-        if e = len then l else cut (rev (tl (rev l))) e
-    in
+    let rec cut l e = if e = (length l) then l else cut (rev (tl (rev l))) e in
     let min a b = if a > b then b else a in
     let len = min (length l) (length m) in
-    List.combine (cut l len) (cut m len)
+    combine (cut l len) (cut m len)
 ;;
 
 (* 4 *)
@@ -51,4 +48,14 @@ let rec lookup l key =
 ;;
 
 (* Challenge *)
-
+let rec coin_permutation l n =
+    let perms coin l =
+        match coin with
+        | i when i < n -> 1 + (coin_permutation l (n - coin))
+        | i when i = n -> 1
+        | _ -> 0
+    in
+    match l with
+    | [] -> 0
+    | h::t -> (perms h t) + (coin_permutation t n)
+;;