Java Binary Search

/*
Java Implementation of Binary Search Algorithm.
- Assuming the Array is Sorted (Ascending Order)
- returns the Index, if Element found.
- -1, if not found.
*/
public class BinarySearch {

    int binarysearch(int[] array, int element) {
        int a_pointer = 0;
        int b_pointer = array.length -1;
      	if (array[a_pointer] == element) return a_pointer;
        if (array[b_pointer] == element) return b_pointer;

        while(a_pointer <= b_pointer){
            int midpoint = a_pointer + (b_pointer - a_pointer) / 2;
          	if (array[midpoint] == element) return midpoint;
          
          	// ignoring the left half, if this is True.
            if (array[midpoint] < element) a_pointer = midpoint + 1;
          
          	// ignoring the right half, if this is True.
            else if (array[midpoint] > element) b_pointer = midpoint - 1;
        }
        return -1;	// Element not Found
    }
    public static void main(String[] args) {
        int[] list = {1, 2, 3, 4, 7, 9, 11, 12, 15, 19, 23, 36, 54, 87};
        System.out.println(binarysearch(list, 19));
    }
}

Binary search java

/*
Order Agnostic Binary Search
-> works for both Ascending and Descending Order Sorted Arrays.
-> Returns the Index Value of the Element in the Array, if found.
-> -1, if not found.
*/

public class OrderAgnosticBinarySearch {

    public static int BinarySearch(int[] array, int element) {
        int a_pointer = 0;
        int b_pointer = array.length - 1;
        boolean isAscending = array[a_pointer] < array[b_pointer];

        if (array[a_pointer] == element) return a_pointer;
        else if (array[b_pointer] == element) return b_pointer;

        while (a_pointer <= b_pointer) {
            int midpoint = a_pointer + (b_pointer - a_pointer) / 2;
            if (array[midpoint] == element) return midpoint;

            if (isAscending){
                if (array[midpoint] < element) a_pointer = midpoint + 1;
                else b_pointer = midpoint - 1;
            }
            else {
                if (array[midpoint] > element) a_pointer = midpoint + 1;
                else b_pointer = midpoint - 1;
            }
        }
        return -1;
    }
  
    public static void main(String[] args) {
        int[] list = {87, 63, 60, 54, 53, 51, 41, 36, 12, -1, -12};
        int[] list2 = {12, 15, 19, 27, 36, 45, 55, 69, 87, 90, 120};
        System.out.println(BinarySearch(list, -1)); // Output: 9
        System.out.println(BinarySearch(list2, 55)); // Output: 6
    }
}

Similar codes

3 votes331 views1 answer
Copy arraylist java
Java
3 votes309 views1 answer
Javafx center node in gridpane
Java
0 vote323 views1 answer
How to Compile the source code in ./src folder with libraries in ./lib folder using JavaSE-1.7
Java
0 vote343 views1 answer
Javac clear
Java
1 vote317 views2 answers
Camel java
Java
4 votes350 views3 answers
Jframe in middle of screen java
Java
5 votes320 views4 answers
File append in java
Java
1 vote326 views1 answer
Stringjoiner stream java
Java
0 vote367 views1 answer
Extract html tag using regex
Java
0 vote290 views1 answer
Produces
Java