bool operator==(BinaryTree& b)
{
if(left.isNull() && b.left.isNull())
return true;
if(left.isNull() || b.left.isNull())
return false;
return (left == b.left && right == b.right) || (left == b.right && right == b.left);
}
string str(bool typeL)
{
if(left.isNull())
return "x";
else
{
return "(" + (typeL == *left < *right ? (*left).str(true) : (*right).str(true)) +
" " + (typeL == *left < *right ? (*right).str(false) : (*left).str(false)) + ")";
}
}