Question

Write a Java program that will

1. create a random list (array)
2. randomize a  search item to be found in the list
3. sequentially search the array for that item. You must code the search and not use a search function.
4. Display each comparison in the array; the element contents and the index.
5. display whether the item was found or not.

Now take that code and alter it to have two lists.

Both lists randomize between 1 and 50.

While traversing one list, use the linear search to compare each element of list 1 to list 2.

Display the element from the first list and whether it matched the element from the second list.  

Perform a binary search with the same list within the same program.  

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// Main.java

public class Main {

      // method to generate an array of given size, initialized with random

      // numbers between 1 and 50

      static int[] generateRandomList(int size) {

            int arr[] = new int[size];

            for (int i = 0; i < size; i++) {

                  arr[i] = (int) (Math.random() * 50) + 1;

            }

            return arr;

      }

      // method to perform linear search on an array for a given element, returns

      // index if found, else -1

      static int linearSearch(int element, int[] array) {

            for (int i = 0; i < array.length; i++) {

                  if (array[i] == element) {

                        // found,

                        return i;

                  }

            }

            // not found

            return -1;

      }

      // method to print elements of an array space separated

      static void printArray(int[] array) {

            for (int i = 0; i < array.length; i++) {

                  System.out.print(array[i] + " ");

            }

            System.out.println();

      }

      // method to sort an array

      static void sortArray(int[] array) {

            // using bubble sort algorithm

            for (int i = 0; i < array.length; i++) {

                  for (int j = 0; j < array.length - 1; j++) {

                        // comparing element at index j to element at index j+1

                        if (array[j] > array[j + 1]) {

                              // swapping elements at j and j+1

                              int t = array[j];

                              array[j] = array[j + 1];

                              array[j + 1] = t;

                        }

                  }

            }

      }

      // method to perform binary search on an array for an element

      static int binarySearch(int element, int[] array) {

            int low = 0, high = array.length - 1, mid;

            // looping as long as low is less than or equal to high

            while (low <= high) {

                  // finding middle index

                  mid = (low + high) / 2;

                  // comparing item at middle with target element

                  if (array[mid] == element) {

                        // found, returning index

                        return mid;

                  } else if (array[mid] > element) {

                        // will search left half on next iteration

                        high = mid - 1;

                  } else {

                        // will search right half on next iteration

                        low = mid + 1;

                  }

            }

            return -1; // not found

      }

      public static void main(String[] args) {

            // generating an array of 10 elements

            int arr1[] = generateRandomList(10);

            // generating a search item

            int search_item = (int) (Math.random() * 50) + 1;

            // flag denoting if item is found

            boolean found = false;

            System.out.println("list1: ");

            // displaying elements before searching

            printArray(arr1);

            // sequentially searching for search_item

            System.out.println("Searching for " + search_item);

            for (int i = 0; i < arr1.length; i++) {

                  // displaying current element and index

                  System.out.println("element: " + arr1[i] + ", index: " + i);

                  if (arr1[i] == search_item) {

                        // found, setting flag to true and exiting loop

                        found = true;

                        break;

                  }

            }

            // displaying if element is found or not

            if (found) {

                  System.out.println("Found!");

            } else {

                  System.out.println("Not found");

            }

            // generating another array of same size (part 2)

            int arr2[] = generateRandomList(10);

            // displaying elements

            System.out.println("\nlist2: ");

            printArray(arr2);

            System.out

                        .println("Searching if each item in list1 is present in list2");

            // looping through each item in list1, checking if it is present in

            // list2

            for (int i = 0; i < arr1.length; i++) {

                  // using linearSearch method to search for arr1[i] in arr2

                  int index = linearSearch(arr1[i], arr2);

                  if (index == -1) {

                        System.out.println(arr1[i] + " is not present in list2");

                  } else {

                        System.out.println(arr1[i] + " is present at index " + index

                                    + " in list2");

                  }

            }

            // now before we perform binary search, the array needs to be sorted. so

            // sorting arr1

            sortArray(arr1);

            //displaying sorted list

            System.out.println("\nlist1 sorted: ");

            printArray(arr1);

            //performing binary search and displaying results

            System.out.println("Searching for " + search_item + " in list1");

            int index = binarySearch(search_item, arr1);

            if (index == -1) {

                  System.out.println(search_item + " is not present in list1");

            } else {

                  System.out.println(search_item + " is present at index " + index

                              + " in list1");

            }

      }

}

/*OUTPUT*/

list1:

48 24 16 8 44 9 43 45 34 43

Searching for 8

element: 48, index: 0

element: 24, index: 1

element: 16, index: 2

element: 8, index: 3

Found!

list2:

14 14 11 39 28 33 16 36 32 21

Searching if each item in list1 is present in list2

48 is not present in list2

24 is not present in list2

16 is present at index 6 in list2

8 is not present in list2

44 is not present in list2

9 is not present in list2

43 is not present in list2

45 is not present in list2

34 is not present in list2

43 is not present in list2

list1 sorted:

8 9 16 24 34 43 43 44 45 48

Searching for 8 in list1

8 is present at index 0 in list1