// Java program to implement interpolation search with recursion
import java.util.*;
class GFG {

	// If x is present in arr[0..n-1], then returns index of it, else returns -1.
	public static int interpolationSearch(int arr[], int lo, int hi, int x)
	{
		int pos;

		// Since array is sorted, an element present in array must be in rangedefined by corner
		if (lo <= hi && x >= arr[lo] && x <= arr[hi]) {

			// Probing the position with keeping uniform distribution in mind.
			pos = lo + (((hi - lo) / (arr[hi] - arr[lo])) * (x - arr[lo]));

			// Condition of target found
			if (arr[pos] == x)
				return pos;

			// If x is larger, x is in right sub array
			if (arr[pos] < x)
				return interpolationSearch(arr, pos + 1, hi, x);

			// If x is smaller, x is in left sub array
			if (arr[pos] > x)
				return interpolationSearch(arr, lo, pos - 1, x);
		}
		return -1;
	}

	// Driver Code
	public static void main(String[] args)
	{

		// Array of items on which search will be conducted.
		int arr[] = { 10, 12, 13, 16, 18, 19, 20, 21, 22, 23, 24, 33, 35, 42, 47 };

		int n = arr.length;

		// Element to be searched
		int x = 18;
		int index = interpolationSearch(arr, 0, n - 1, x);

		// If element was found
		if (index != -1)
			System.out.println("Element found at index "+ index);
		else
			System.out.println("Element not found.");
	}
}