Chapter 21, Problem 5AW

Explanation of Solution

Algorithm for a method “contains” to search a value of “x”:

Step 1: Define the method name “contains ()” which contains the node and search element as the parameters.

Step 2: Check if the value of node is equal to null. If it is equal, then return “false”.

Step 3: Check if the value of node is equal to the search element. If this condition is true, then return “true”.

Step 4: Again check if the search element is present in the left side of the tree by calling the function “contains ()” recursively and return “true” if the search element is present.

Step 5: Again check if the search element is present in the right side of the tree by calling the function “contains ()” recursively and return “true” if the search element is present.

Step 6: Finally, if the search element is not present, then return “false”.

A method “contains” to search a value of “x”:

//Function definition for "contains"

boolean contains(Node binarytree, int x)

{

    //Check if the value of node is equal to null

    if (binarytree == null)

        //Return false

        return false;

//Check if the value of node is equal to the search element

    if (binarytree.value == x)

        //Return true

        return true;

//Check if the search element is present in the left sub-tree

    if (contains(binarytree...