r.c

#include<stdio.h>
//using namespace std;
 
// Returns count of rotations for an array which
// is first sorted in ascending order, then rotated
int countRotations(int arr[], int low, int high)
{
    // This condition is needed to handle the case
    // when array is not rotated at all
    if (high < low)
        return 0;
 
    // If there is only one element left
    if (high == low)
        return low;
 
    // Find mid
    int mid = low + (high - low)/2; /*(low + high)/2;*/
 
    // Check if element (mid+1) is minimum element.
    // Consider the cases like {3, 4, 5, 1, 2}
    if (arr[mid+1] < arr[mid])
       return (mid+1);
 
    // Check if mid itself is minimum element
    if ( arr[mid] < arr[mid - 1])
       return mid;
 
    // Decide whether we need to go to left half or
    // right half
    if (arr[high] > arr[mid])
       return countRotations(arr, low, mid-1);
 
    return countRotations(arr, mid+1, high);
}
 
// Driver code
int main()
{
    int arr[] = {7, 9,11, 13,15,16};
    int n = sizeof(arr)/sizeof(arr[0]);
   // int p=countRotations(arr,0,n);
printf("%d",countRotations(arr,0,n-1));
    return 0;
}