2 files changed, 24 insertions, 0 deletions
diff --git a/prolog/problems/trees/mirrorbt_2/common.py b/prolog/problems/trees/mirrorbt_2/common.py
new file mode 100644
index 0000000..dc8d337
--- /dev/null
+++ b/prolog/problems/trees/mirrorbt_2/common.py
@@ -0,0 +1,12 @@
+id = 136
+group = 'trees'
+number = 43
+visible = True
+facts = None
+
+solution = '''\
+mirrorBT(nil, nil).
+mirrorBT(b(L, X, R), b(NewR, X, NewL)) :-
+  mirrorBT(L, NewL),
+  mirrorBT(R, NewR).
+'''
diff --git a/prolog/problems/trees/mirrorbt_2/en.py b/prolog/problems/trees/mirrorbt_2/en.py
new file mode 100644
index 0000000..d44f463
--- /dev/null
+++ b/prolog/problems/trees/mirrorbt_2/en.py
@@ -0,0 +1,12 @@
+id = 136
+name = 'mirrorBT/2'
+slug = 'flip a binary tree horizontally'
+
+description = '''\
+<p><code>mirrorBT(T, NewT)</code>: the binary tree <code>NewT</code> is obtained from <code>T</code> by flipping it over the vertical axis through the root node.</p>
+<pre>
+  ?- mirrorBT(b(b(b(nil,4,nil),2,b(nil,5,nil)),1,b(nil,3,nil)), X).
+    X = b(b(nil,3,nil), 1, b(b(nil,5,nil), 2, b(nil,4,nil))).
+</pre>'''
+
+hint = {}