programming-examples/java/Searching_Sorting_Algorithms/Java Program to Perform Uniform Binary Search.java

/*This is a java program to perform uniform binary search technique. It uses a lookup table to update a single array index,
rather than taking the midpoint of an upper and a lower bound on each iteration; therefore, it is optimized for architectures
(such as Knuth’s MIX) on which a table look-up is generally faster than an addition and a shift,
and many searches will be performed on the same array, or on several arrays of the same length.*/

//This is a java program to perform uniform binary search.
import java.util.Random;
import java.util.Scanner;

public class Uniform_Binary_Search
{
    static int N = 10;
    static int[] sequence = new int[N];
    static int[] delta = new int[42];

    public static void sort()
    {
        int i, j, temp;
        for (i = 1; i < N; i++)
            {
                j = i;
                temp = sequence[i];
                while (j > 0 && temp < sequence[j - 1])
                    {
                        sequence[j] = sequence[j - 1];
                        j = j - 1;
                    }
                sequence[j] = temp;
            }
    }

    public static void make_delta(int N)
    {
        System.out.println();
        int power = 1;
        int i = 0;
        do
            {
                int half = power;
                power <<= 1;
                delta[i] = (N + half) / power;
            }
        while (delta[i++] != 0);
    }

    public static int unisearch(int key)
    {
        int i = delta[0] - 1; /* midpoint of array */
        int d = 0;
        while (true)
            {
                if (key == sequence[i])
                    return i;
                else if (delta[d] == 0)
                    return -1;
                else
                    {
                        if (key < sequence[i])
                            i -= delta[++d];
                        else
                            i += delta[++d];
                    }
            }
    }

    public static void main(String args[])
    {
        Random random = new Random();
        for (int i = 0; i < N; i++)
            sequence[i] = Math.abs(random.nextInt(100));
        System.out.println("The sequence is :");
        sort();
        for (int i = 0; i < N; i++)
            System.out.print(sequence[i] + " ");
        //sort();
        make_delta(N);
        System.out.println("Enter the element to be searched: ");
        Scanner sc = new Scanner(System.in);
        int key = sc.nextInt();
        int p = unisearch(key);
        if (p > 0)
            System.out.println("Element found at position " + p);
        else
            System.out.println("Element doesn't exist");
        sc.close();
    }
}

/*
The sequence is :
12 13 20 24 27 32 63 64 74 82
Enter the element to be searched:
24
Element found at position 3

The sequence is :
0 30 31 32 37 48 51 58 78 87
Enter the element to be searched:
98
Element doesn't exist