jump_search.java

public class JumpSearch
{
    public static int jumpSearch(int[] arr, int i)
    {
        int n = arr.length;
 
        // Finding block size to be jumped
        int step = (int)Math.floor(Math.sqrt(n));
 
        // Finding the block where element is present
        // (if it is present)
        int prev = 0;
        while (arr[Math.min(step, n)-1] < i)
        {
            prev = step;
            step += (int)Math.floor(Math.sqrt(n));
            if (prev >= n)
                return -1;
        }
 
        // Doing a linear search for i in block
        // beginning with prev.
        while (arr[prev] < i)
        {
            prev++;
 
            // If we reached next block or end of array
            // element is not present.
            if (prev == Math.min(step, n))
                return -1;
        }
 
        // If element is found
        if (arr[prev] == i)
            return prev;
 
        return -1;
    }
 
    // Driver program to test function
    public static void main(String [ ] args)
    {
        int arr[] = { 0, 1, 1, 2, 3, 5, 8, 13, 21,
                    34, 55, 89, 144, 233, 377, 610};
        int i = 55;
 
        // Find the index of 'i' using Jump Search
        int index = jumpSearch(arr, i);
 
        // Print the index where 'i' is located
        System.out.println("\nNumber " + i +
                            " is at index " + index);
    }
}