tragaperrasRIGHT.java

/*
*In an array a
*figures out the element e
*in an index after performing r RIGHT rotations
*/
public class Tragaperras {
       static int circularRightArrayRotation(int[] a, int r, int index) {
        int l = a.length;
        int R = r - (r/l*l);
        //Get rid of over-rotations
        //E.g 
        //length of array = 5
        //rotations = 13
        //we will only have to perform 2 rotations.
        //13 - ((13/2)*5)
    
        int e = 0;//element in index after rotations
            int resultIndex = index - R;
            if(resultIndex < 0){
                resultIndex = a.length + resultIndex; 
                e = a[resultIndex]; 
            }else{
                e = a[resultIndex]; 
            }
        
        return e; 
    }    
       
    //PRO VERSION (same O(1) complexity, less code)
    /*
    static int circularArrayRotation(int[] a, int r, int index) {
        int l = a.length;
        int R = r - (r/l*l);
        int result = 0;
        int resultIndex = index - R;
        return (resultIndex < 0) ? a[l+resultIndex] : a[resultIndex];
    }   
    */


    public static void main(String[] args) {
    	int[] a = {1, 2, 3};
    	int r = 2;
    	int index = 0; 
        System.out.println(circularRightArrayRotation(a, r, index));
    }
}