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RotationCount.java
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RotationCount.java
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public class RotationCount{
public static void main(String[] args) {
int[] arr = {4,5,6,7,10,1,2,3};
System.out.println(CountRotations(arr));
}
static int CountRotations(int[] arr){
int pivot = findPivot(arr);
return pivot + 1;
}
static int findPivot(int[] arr){
int start = 0;
int end = arr.length -1;
while (start <= end){
int mid = start + (end - start)/2;
if (mid< end && arr[mid] > arr[ mid +1]){
return mid;
}else if (mid > start && arr[mid] < arr[mid - 1]){
return mid -1;
}else if (arr[start] >= arr[mid]){
end = mid -1;
}else {
start = mid +1 ;
}
}
return -1;
}
static int findPivotWithDuplicates(int[] arr){
int start =0 ;
int end = arr.length -1;
while (start < end){
int mid = start + (end - start)/2;
if (mid < end && arr[mid] > arr[mid +1]){
return mid;
} else if(mid > start && arr[mid]< arr[mid-1]){
return mid -1;
} else if (arr[mid] == arr[start] && arr[mid] == arr[end]){
if(arr[start] > arr[start +1] ){
return start ;
}
start++ ;
}
}
return end;
}
}