added example 2.9.1_21

2.9.1_21.pl

+% nacteni:
+/* ['2.9.1_21.pl']. */
+
+
+path(A,Z,Graph,Cesta) :- path1(A,[Z],Graph,Cesta).
+
+path1(A,[A|Cesta1],_,[A|Cesta1]).
+path1(A,[Y|Cesta1],Graph,Cesta) :- adjacent(X,Y,Graph),
+    \+ member(X,Cesta1),path1(A,[X,Y|Cesta1],Graph,Cesta).
+
+adjacent(X,Y,graph(_,Edges)) :- member(e(X,Y),Edges)
+                                    ;member(e(Y,X),Edges).
+
+graph([a,b,c,d],[e(a,b),e(b,d),e(b,c),e(c,d)]).
+
+% demonstracni vypis
+
+start:- 
+    write('Cesta v grafu'),nl, nl,
+    write('path(a, c, graph, Cesta) : '),
+    graph(Nodes,Edges),
+    path(a, c, graph(Nodes,Edges), Cesta),
+    write(Cesta), nl, nl.
+
+?-start.
+

2.9.1_21.py

+#!/usr/bin/env python
+# encoding=utf-8 (pep 0263)
+
+from linked_lists import LinkedList, Cons, Nil
+
+def path(a, z, graph):
+    for cesta in path1(a, LinkedList(z), graph, 1):
+        yield cesta
+
+def path1(a, akumulator_cesty, graph, depth):
+    if akumulator_cesty.head == a:
+        yield akumulator_cesty
+    else:
+        y = akumulator_cesty.head
+        for x in adjacent_anyX(y, graph):
+            if not member(x, akumulator_cesty):
+                for cesta in path1(a, Cons(x, akumulator_cesty), graph, depth+1):
+                    yield cesta
+
+def adjacent_anyX(y, graph):
+    _, edges = graph
+    for a, b in member_anyX(edges):
+        if y == a:
+            yield b
+        if y == b:
+            yield a
+
+def member(x, xs):
+    if xs == Nil:
+        return False
+    if x == xs.head:
+        return True
+    return member(x, xs.tail)
+
+def member_anyX(xs):
+    if xs == Nil:
+        return
+    yield xs.head
+    for x in member_anyX(xs.tail):
+        yield x
+
+_graph = (LinkedList("a", "b", "c", "d"),
+          LinkedList(("a", "b"), ("b", "d"), ("b", "c"), ("c", "d")))
+
+# demonstracni vypis
+if __name__ == "__main__":
+    print('Cesta v grafu\n')
+    print('next(path("a", "c", _graph)) : %s' % next(path("a", "c", _graph)))

2.9.1_21.py.out

+Cesta v grafu
+
+next(path("a", "c", _graph)) : [a, b, c]

Makefile

 .PHONY: tests output pylint2 pylint3
 
 IGNORED_PYLINT_TESTS=invalid-name missing-docstring \
-	redefined-variable-type too-few-public-methods
-IGNORED_PYLINT2_TESTS=superfluous-parens duplicate-code
-IGNORED_PYLINT3_TESTS=duplicate-code
+	redefined-variable-type too-few-public-methods duplicate-code
+IGNORED_PYLINT2_TESTS=superfluous-parens
+IGNORED_PYLINT3_TESTS=
 
 tests:
 	# all tests