2 files changed, 69 insertions, 0 deletions
diff --git a/prolog/problems/license_plates/checklicenseplate_3/common.py b/prolog/problems/license_plates/checklicenseplate_3/common.py
new file mode 100644
index 0000000..f926481
--- /dev/null
+++ b/prolog/problems/license_plates/checklicenseplate_3/common.py
@@ -0,0 +1,52 @@
+id = 148
+group = 'license_plates'
+number = 55
+visible = True
+facts = None
+
+solution = '''\
+conc148([], L, L).
+conc148([H|T], L2, [H|L]) :-
+  conc148(T, L2, L).
+
+memb148(X, [X|_]).
+memb148(X, [_|T]) :-
+  memb148(X, T).
+
+getdigits148([], []).
+getdigits148([X|T], [X|NT]) :-
+  number(X), !,
+  getdigits148(T, NT).
+getdigits148([_|T], NT) :-
+  getdigits148(T, NT).
+
+joindigits148([X], [X]).
+joindigits148([X,Y|T], NT) :-
+  XY is 10*X + Y,
+  joindigits148([XY|T], NT).
+joindigits148([X,Y|T], [X|NT]) :-
+  joindigits148([Y|T], NT).
+
+genexp148([Exp], Exp).
+genexp148(L, Exp) :-
+  conc148(Before, [N1,N2|After], L),
+  memb148(Op, ['+','-','*','/']),
+  NExp =.. [Op, N1, N2],
+  conc148(Before, [NExp|After], L1),
+  genexp148(L1, Exp).
+
+firstMinus148(L, L).
+firstMinus148([X|T], [Y|T]) :-
+  Y is -X.
+
+checkLicensePlate(LP, E1, E2) :-
+  getdigits148(LP, Digs),
+  conc148(L1, L2, Digs),
+  joindigits148(L1, N1),
+  joindigits148(L2, N2),
+  firstMinus148(N1, MN1),
+  firstMinus148(N2, MN2),
+  genexp148(MN1, E1),
+  genexp148(MN2, E2),
+  E1 =:= E2.
+'''
diff --git a/prolog/problems/license_plates/checklicenseplate_3/en.py b/prolog/problems/license_plates/checklicenseplate_3/en.py
new file mode 100644
index 0000000..1f3ea94
--- /dev/null
+++ b/prolog/problems/license_plates/checklicenseplate_3/en.py
@@ -0,0 +1,17 @@
+id = 148
+name = 'checkLicensePlate/3'
+slug = 'check if the numbers in a license plate form an equation'
+
+description = '''\
+<p><code>checkLicensePlate(LP, E1, E2)</code>: the digits in the list <code>LP</code> can be combined into a valid equation <code>E1</code> = <code>E2</code>. <code>E1</code> and <code>E2</code> are arithmetic expressions, obtained from sublists of <code>Plate</code> by inserting arithmetic operators (<code>+</code>, <code>-</code>, <code>*</code> and <code>/</code>) between elements. An additional unary minus can be inserted before the leftmost number of <code>E1</code> and <code>E2</code>.</p>
+<pre>
+  ?- checkLicensePlate([l,j,l,3,-,2,1,7], E1, E2).
+    E1 = 3,       E2 = 21/7 ;
+    E1 = -3,      E2 = -21/7 ;
+    E1 = 3*2,     E2 = -1+7 ;
+    E1 = -3*2,    E2 = 1-7 ;
+    E1 = 3*2+1,   E2 = 7 ;
+    E1 = -3*2-1,  E2 = -7.
+</pre>'''
+
+hint = {}