added example 2.9.2_22

2.9.2_22.pl

+% nacteni:
+/* ['2.9.2_22.pl']. */
+
+path(A,Z,Graf,Cesta,Cena) :- path1(A,[Z],0,Graf,Cesta,Cena).
+
+path1(A,[A|Cesta1],Cena1,_,[A|Cesta1],Cena1).
+path1(A,[Y|Cesta1],Cena1,Graf,Cesta,Cena) :- adjacent(X,Y,CenaXY,Graf),
+    \+ member(X,Cesta1),Cena2 is Cena1+CenaXY,
+    path1(A,[X,Y|Cesta1],Cena2,Graf,Cesta,Cena).
+    
+adjacent(X,Y,CenaXY,Graf) :- member(X-Y/CenaXY,Graf);member(Y-X/CenaXY,Graf).
+
+start:- 
+    write('Cesta v grafu'),nl, nl,
+    path(s, u, [s-t/3, t-v/1, t-u/5, u-t/2, v-u/2], Cesta, Cena),
+    write('Cesta='), write(Cesta), nl,
+    write('Cena='), write(Cena), nl, nl.
+
+?-start.

2.9.2_22.py

+#!/usr/bin/env python
+# encoding=utf-8 (pep 0263)
+
+from linked_lists import LinkedList, Cons, Nil
+
+def path(a, z, graph):
+    for cesta, cena in path1(a, LinkedList(z), 0, graph, 1):
+        yield (cesta, cena)
+
+def path1(a, akumulator_cesty, akumulator_ceny, graph, depth):
+    if akumulator_cesty.head == a:
+        yield (akumulator_cesty, akumulator_ceny)
+    else:
+        y = akumulator_cesty.head
+        for x, cenaXY in adjacent_anyXcenaXY(y, graph):
+            if not member(x, akumulator_cesty):
+                for cesta, cena in path1(a, Cons(x, akumulator_cesty),
+                                         akumulator_ceny + cenaXY, graph, depth+1):
+                    yield (cesta, cena)
+
+def adjacent_anyXcenaXY(y, edges):
+    for a, b, cenaAB in member_anyX(edges):
+        if y == a:
+            yield (b, cenaAB)
+        if y == b:
+            yield (a, cenaAB)
+
+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
+
+# demonstracni vypis
+if __name__ == "__main__":
+    print('Cesta v grafu\n')
+    cesta_, cena_ = next(path("s", "u", LinkedList(
+        ("s", "t", 3), ("t", "v", 1), ("t", "u", 5), ("u", "t", 2), ("v", "u", 2))))
+    print('Cesta=%s' % cesta_)
+    print('Cena=%d\n' % cena_)

2.9.2_22.py.out

+Cesta v grafu
+
+Cesta=[s, t, u]
+Cena=8
+