Method compare

RankTransformofanArray.java:10–12

(Integer x, Integer y)

        }
        Collections.sort(indexArr, new Comparator<Integer>(){
            public int compare(Integer x, Integer y){
                return arr[x] - arr[y]; //cust comp, inc sort
            }
        });
        int rank=0;
        int prev=Integer.MAX_VALUE;