Data commit

Task/Matrix-transposition/Prolog/matrix-transposition.pro

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+% transposition of a rectangular matrix
+% e.g.   [[1,2,3,4], [5,6,7,8]]
+% give [[1,5],[2,6],[3,7],[4,8]]
+
+transpose(In, Out) :-
+    In = [H | T],
+    maplist(initdl, H, L),
+    work(T, In, Out).
+
+% we use the difference list to make "quick" appends (one inference)
+initdl(V, [V | X] - X).
+
+work(Lst, [H], Out) :-
+	maplist(my_append_last, Lst, H, Out).
+
+work(Lst, [H | T], Out) :-
+    maplist(my_append, Lst, H, Lst1),
+    work(Lst1, T, Out).
+
+my_append(X-Y, C, X1-Y1) :-
+    append_dl(X-Y, [C | U]- U, X1-Y1).
+
+my_append_last(X-Y, C, X1) :-
+	append_dl(X-Y, [C | U]- U, X1-[]).
+
+% "quick" append
+append_dl(X-Y, Y-Z, X-Z).