Question

I wrote a method that checks if two binary tree are equal.

Is this correct or is there a better way?

public  boolean equal(BinaryNode t1, BinaryNode t2){  
    if(t1==null || t2==null)  
        return false;  
    else if(t1.element != t2.element)  
        return false;  
    else if(equal(t1.left,t2.left))   
        return false;  
    else if(equal(t1.right,t2.right))   
        return false;  
    else  
        return true;
}  

Answer 1

The following is probably closer to the logic you’re looking for, but is completely untested and was written in this text field:

if (t1==null && t2==null)
    return true;
if (t1.element != t2.element)
    return false;
return equal(t1.left, t2.left) && equal(t1.right, t2.right);

There are a lot of flaws in your current version.