Java Program to Perform Binary Search inwards Array without Recursion

The binary search algorithm is used to search an chemical ingredient inwards the sorted array. It's faster than linear search together with improves functioning from O(n) to O(logN) for searching an chemical ingredient inwards the array. In gild to perform the binary search, you lot demand a sorted array, therefore you lot tin either inquire the user to acquire into array inwards sorted gild or you lot should sort the array earlier performing the binary search. In this article, nosotros volition write a Java plan which volition convey input from the user, both array together with the set out to live on searched together with and therefore perform a binary search to discovery that set out inwards given array. We'll non usage the Collections.binarySearch() method instead we'll write our ain because it's a programming exercise to examination one's coding skill. In gild to implement binary search, you lot must outset know how binary search works? If you lot don't know the algorithm you lot cannot code it. So, let's outset revise the binary search algorithm itself.

How Binary Search Algorithm works

If you lot recollect something nigh searching algorithms from your information construction together with algorithm classes inwards Engineering college you lot mightiness know that binary search industrial plant on the regulation of divide together with conquer. In this technique, a solution is constitute past times dividing the input on simply about rules.

In binary search algorithm, you lot outset discovery the middle chemical ingredient of the array together with compare that amongst the set out you lot are searching. If it's equal together with therefore you lot provide truthful or index of that set out together with your binary search is consummate but if it doesn't check together with therefore you lot split upwardly the array inwards 2 business office based upon whether the middle chemical ingredient is greater than or less than the cardinal value, which you lot are searching.

If the cardinal is greater than middle chemical ingredient than search values inwards the minute one-half of array because the array is sorted inwards increasing order. Similarly, if the cardinal is lower than middle chemical ingredient it agency it's inwards the outset business office of the array.

After each iteration you lot dominion out one-half of array elements. Which agency if you lot own got 100 elements inwards the array together with therefore you lot demand O(log2 100) i.e. 10 iterations to genuinely discovery the value or confirm that it doesn't be inwards the array.

If you lot are non certain nigh how to calculate fourth dimension together with infinite complexity of an algorithm, you lot should refer to a practiced information construction together with algorithm mass similar Introduction to Algorithms past times Thomas Cormen. It's essential from the interview betoken of stance to live on able to discovery out fourth dimension together with infinite complexity of whatever algorithm.

s faster than linear search together with improves functioning from Java Program to Perform Binary Search inwards Array without Recursion

Several of import information construction e.g. binary search tree together with binary heap are based upon the binary search algorithm, that's why it becomes real of import for whatever programmer to empathise together with implement this algorithm past times hand.

Binary search is naturally a recursive algorithm because what you lot are doing is essentially a binary search at smaller input afterward each iteration, but inwards this program, we'll implement binary search without recursion. This is to gear upwardly you lot good for your interviews because oft Interviewer asks the candidate to write both iterative together with recursive solution of a work e.g.

Iterative together with Recursive way to opposite String (check here)
Printing Fibonacci serial amongst together with without recursion (see here)
Finding length of linked listing using iteration together with recursion (see here)

Here is a flowchart of the binary search algorithm, which volition explicate what I said to a greater extent than clearly, recollect 1 motion-picture demonstrate is worth to a greater extent than than one thousand words.

How to implement Binary Search inwards Java

Here is our implementation of the pop binary search algorithm inwards Java. Though, you lot don't demand to implement this algorithm if you lot desire to usage it inwards your production code. JDK collection API already has a binarySearch() method on the Arrays class. This implementation is for educational usage to learn students how to code binary search inwards Java.

import java.util.Scanner;  /*  * Java Program to implement binary search without using recursion  */ public class BinarySearch {      public static void main(String[] args) {          Scanner commandReader = new Scanner(System.in);         System.out.println("Welcome to Java Program to perform binary search on int array");         System.out.println("Enter full set out of elements : ");         int length = commandReader.nextInt();         int[] input = new int[length];          System.out.printf("Enter %d integers %n", length);         for (int i = 0; i < length; i++) {             input[i] = commandReader.nextInt();         }          System.out.println("Please acquire into set out to live on searched inwards array (sorted order)");         int cardinal = commandReader.nextInt();          int index = performBinarySearch(input, key);          if (index == -1) {             System.out.printf("Sorry, %d is non constitute inwards array %n", key);         } else {             System.out.printf("%d is constitute inwards array at index %d %n", key, index);         }          commandReader.close();      }      /**      * Java method to perform binary search. It convey an integer array together with a      * set out together with provide the index of set out inwards the array. If set out doesn't      * exists inwards array together with therefore it provide -1      *      * @param input      * @param set out      * @return index of given set out inwards array or -1 if non constitute      */     public static int performBinarySearch(int[] input, int number) {         int depression = 0;         int high = input.length - 1;          while (high >= low) {             int middle = (low + high) / 2;             if (input[middle] == number) {                 return middle;             } else if (input[middle] < number) {                 depression = middle + 1;             } else if (input[middle] > number) {                 high = middle - 1;             }         }         return -1;     }  }   Output Welcome to Java Program to perform binary search on int array Enter full set out of elements :  4 Enter 4 integers  10 20 20 34 Please enter set out to live on searched in array 34 34 is constitute in array at index 3   Welcome to Java Program to perform binary search on int array Enter full set out of elements :  7 Enter 7 integers  1 2 3 4 5 6 7 Please enter set out to live on searched in array 10 Sorry, 10 is not constitute in array

That's all nigh how to implement binary search inwards Java without using recursion. This is an iterative solution of the binary search problem. The fourth dimension complexity of binary search is inwards gild of O(logN) if you lot acquire the sorted input. If you lot own got to variety the input together with therefore you lot demand to add together that fourth dimension on the full run fourth dimension of the algorithm every bit well. If you lot own got non read already together with therefore you lot should read Introduction to Algorithms to larn to a greater extent than nigh how to calculate fourth dimension together with infinite complexity of an algorithm.

Further Reading
Algorithms together with Data Structures - Part 1 together with 2
Java Fundamentals, Part 1 together with 2
Cracking the Coding Interview - 189 Questions together with Solutions