Bnb tries fixed for examples

[NeoZ666]

No description provided.

[delcin-raj]

The decrement should happen after checking if bnb_tries is non zero

[delcin-raj]

Every bnb recursive invocation is referring the global bnb_tries variable (global for the recursive function calls).

So it is enough to check at the beginning and decrement at the beginning, because the successive recursive calls will terminate if the tries ever became zero.

We also should not decrement when it goes to zero, that's why we check for zero before decrementing.