CODEWITHSUNDEEP
prolog
Panna Das
Panna Das

Reputation: 11

Element to search in binary tree in Prolog

I'm very new to Prolog, and trying to find an element to search in binary tree, it finds it successfully but the problem is if it doesn't it still gives yes, I want it to say no or to say not found. My code is:

child(1,2,3).
child(2,4,5).
child(3,6,7).
node(1,a).
node(2,b).
node(3,c).
node(4,d).
node(5,f).
node(6,f).
node(7,g).


show(X):-
    write('element is found in node: '),write(X),nl.
inc(X,Y,Z):-
    Y is X+X,
    Z is X+X+1.


find(A):-
    traverse3(1,A).
traverse3(X,A):-
    check(X,A),
    inc(X,Y,Z),
    child(X,Y,Z),
    traverse3(Y,A),
    traverse3(Z,A).

check(X,A):- not(node(X,A)).

check(X,A):- 
    node(X,A),
    show(X).
traverse3(X,A):- not(child(X,Y,Z)).

Upvotes: 1

Views: 706

Answers (1)

user1812457
user1812457

Reputation:

This is an unusual binary tree. But anyway, since you have already "normalized" it to a database representation, all you have to do to find an element is to ask for it.

In other words, if your program tree.pl consists only of the child/3 and node/2 facts:

child(1,2,3).
child(2,4,5).
child(3,6,7).
node(1,a).
node(2,b).
node(3,c).
node(4,d).
node(5,f).
node(6,f).
node(7,g).

You can simply query for the element you need:

?- [tree].
true.

?- node(N, a).
N = 1.

?- node(N, f).
N = 5 ;
N = 6.

?- node(4, E).
E = d.

?- node(N, E).
N = 1, E = a ;
N = 2, E = b ;
N = 3, E = c ;
N = 4, E = d ;
N = 5, E = f ;
N = 6, E = f ;
N = 7, E = g.

Or is there something I am missing?

Upvotes: 1

Related Questions