searchinRotatedarray.java

class Main {

    static int pivotedBinarySearch(int arr[], int n,
                                   int key)
    {
        int pivot = findPivot(arr, 0, n - 1);
        if (pivot == -1)
            return binarySearch(arr, 0, n - 1, key);
        if (arr[pivot] == key)
            return pivot;
        if (arr[0] <= key)
            return binarySearch(arr, 0, pivot - 1, key);
        return binarySearch(arr, pivot + 1, n - 1, key);
    }
 
    static int findPivot(int arr[], int low, int high)
    {
   
        if (high < low)
            return -1;
        if (high == low)
            return low;
        int mid = (low + high) / 2;
        if (mid < high && arr[mid] > arr[mid + 1])
            return mid;
        if (mid > low && arr[mid] < arr[mid - 1])
            return (mid - 1);
        if (arr[low] >= arr[mid])
            return findPivot(arr, low, mid - 1);
        return findPivot(arr, mid + 1, high);
    }
    static int binarySearch(int arr[], int low, int high,
                            int key)
    {
        if (high < low)
            return -1;
        int mid = (low + high) / 2;
        if (key == arr[mid])
            return mid;
        if (key > arr[mid])
            return binarySearch(arr, (mid + 1), high, key);
        return binarySearch(arr, low, (mid - 1), key);
    }
    public static void main(String args[])
    {
        int arr1[] = { 5, 6, 7, 8, 9, 10, 1, 2, 3 };
        int n = arr1.length;
        int key = 3;
        System.out.println(
            "Index of the element is : "
            + pivotedBinarySearch(arr1, n, key));
    }
}