Longest common prefix: Difference between revisions

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 =={{header|Erlang}}==
-A bow to the perversion of the Scala implementation. Not canonical erlang, this.
-{{trans|Scala}}
 <lang erlang>
 -module(lcp).
--export([ main/1 ]).
+-export([ main/0 ]).
+data() -> [
-shortest(List,Size) when length(List) =:= 0 ->
+    ["interspecies", "interstellar", "interstate"],
-    Size;
+    ["throne", "throne"],
+    ["throne", "dungeon"],
+    ["throne", "", "throne"],
+    ["cheese"],
+    [""],
+    [],
+    ["prefix", "suffix"],
+    ["foo", "foobar"]
+  ].
+main() -> [io:format("~p -> \"~s\"~n",[Strs,lcp(Strs)]) || Strs <- data()].
-shortest(List,Size) ->
-    [H|T] = List,
-    if
-      length(H) < Size ->
-         shortest(T, length(H) );
-       true ->
-         shortest(T, Size )
-end.
-uniq(List, Size ) ->
+lcp(      []) -> [];
+lcp([S|Strs]) -> lists:foldl( fun(X,Y) -> lcp(X,Y,[]) end, S, Strs).
-    First = string:substr(hd(List),1,Size),
-    Last = string:substr(lists:last(List),1,Size),
-    Ttuples = lists:zip(First, Last),
-    % this is the bit that is like the scala version
-    TheList = lists:takewhile(
-        fun(E) ->
-          case element(1,E) =:= element(2,E) of true -> true;
-          _ -> false
-          end
-        end, Ttuples),
-    Prefix = length(TheList),
-    io:format("Prefix: ~p~n", [string:substr(First,1,Prefix)]).
-main(List) ->
-      Sorted = lists:sort(List),
-      if
-        length(List) < 2 ->
-          io:format("Prefix empty:$~p~n",[List]);
-        true ->
-          Size = length(hd(List)),
-          uniq(Sorted, shortest(Sorted,Size))
-      end.
+lcp([X | Xs], [X | Ys], Pre) -> lcp(Xs, Ys, [X|Pre]);
+lcp(_, _, Pre) -> lists:reverse(Pre).
+</lang>
-</lang>
 {{out}}
 <pre>
+["interspecies","interstellar","interstate"] -> "inters"
-> Data =
+["throne","throne"] -> "throne"
-[["interspecies","interstellar","interstate"],
- ["throne","throne"],
+["throne","dungeon"] -> ""
- ["throne","dungeon"],
+["throne",[],"throne"] -> ""
- ["throne",[],"throne"],
+["cheese"] -> "cheese"
+[[]] -> ""
- ["cheese"],
+[] -> ""
- [[]],
+["prefix","suffix"] -> ""
- [],
- ["prefix","suffix"],
+["foo","foobar"] -> "foo"
- ["foo","foobar"],
- ["foreign","forsake","forget","forlorn","forgiven"]].
-> [lcp:main(X) || X <- Data].
-Prefix: "inters"
-Prefix: "throne"
-Prefix: []
-Prefix: []
-Prefix empty:$["cheese"]
-Prefix empty:$[[]]
-Prefix empty:$[]
-Prefix: []
-Prefix: "foo"
-Prefix: "for"
-[ok,ok,ok,ok,ok,ok,ok,ok,ok,ok]
 </pre>