Getting Familiar With Search Algorithms

Search Algorithms are the methods of searching a particular element from a list of elements as well as finding their position in that list. These algorithms are classified into two types based on the way of performing searches as described below :

1. LINEAR SEARCH :

It is the simplest search algorithm for searching a particular element from a list. Steps to be performed :

• It starts from the beginning of the list.
• Goes till the end of the list by comparing each element with the element that needed to be searched.
• If the element matches with the searched element, it returns its index in that array.
• If not, then returns an element not found in the list.

You can use this algorithm for both integers as well as string elements you need to search in the list.

Program for Integer Array :

public class LinearSearch {

public static void main(String[] args) {

int arr[]= {5,23,40,17,3,19,10}; //Array declaration

int element=10; //Element to be searched

int flag=0;

for(int i=0; i<arr.length;i++) { //Iterating elements of the array

if(arr[i]==element) {

System.out.println("Element is present at "+i+" index position");

flag=flag+1;

}

}

if(flag==0){

System.out.println("Searched Element not present in the list");

}

}

}

Program for String Array :

public class LinearSearch {

public static void main(String[] args) {

String[] arr= {"roshni", "deepak", "rohan", "shivani"}; //Array declaration for string

String element="rohan"; //String to be searched

int flag=0;

for(int i=0; i<arr.length;i++) { //Iterating elements of the array

if(arr[i].equals(element)){

System.out.println("Item present in "+i+" index position");

flag=flag+1;

}

}

if(flag==0) {

System.out.println("Item not found in the list");

}

}

}

2. BINARY SEARCH :

This algorithm is based on the technique of divide and conquer which means it first divides the array in two halves. Then starts searching for a particular element in that sorted array. This process is repeated until it finds the element. Steps to be performed :

• Compare the element to be searched with the middle element.
• If the searched element matches with the middle element, it returns the index of the middle element.
• Else if the searched element is greater than the middle element, then that element will only be present in the right half subarray after the middle element. Therefore elements will be searched there by performing divide and conquer technique.
• Else if the searched element is smaller than the middle element, then that element will be present in the left half subarray. So we perform searching in the left half subarray.

NOTE : Binary Search is always applied to the sorted data, so make sure you perform it only to the list of sorted data elements.

Program :

public class BinarySearch {

public static void main(String[] args) {

int arr[]= {3,12,6,5,7,8,10,15};

int element=7; //Element to be searched

int left=0;

int right=arr.length-1;

int middle=(left+right)/2;

while(left<=right){ //Iterating elements

if(arr[middle]==element){

System.out.println("Element is at "+middle+ " index position");

break;

}else if(arr[middle]<element){

left=middle+1;

}else{

right=middle-1;

}middle=(left+right)/2;

}

if(left>right){

System.out.println("Element not found");

}

}

}

We are an Web development company that provides complete enterprise solutions with focus on building custom software applications. Our 360-degree Web development services enable organizations to streamline their business processes, enhance productivity, and improve operational efficiency. For more information, contact us at [email protected].