means of an array list such that node of is the element of at index (vas mentioned in the previous we realize the array list by means of an extendable array (see section such an implementation is simple and efficientfor we can use it to easily perform the methods rootparentleftrighthaslefthasrightisinternalisexternaland isroot by using simple arithmetic operations on the numbers (vassociated with each node involved in the operation we leave the details of this implementation as an exercise ( - we show an example array-list representation of binary tree in figure figure representation of binary tree by means of an array list