GCJ 2012 - Recycled Numbers

RecycledNumbers.java

import java.util.HashSet;

/**
 *
 * @author Babji Prashanth, Chetty
 */
public class RecycledNumbers {
    public int findNumberOfPairs(int A, int B) {
        int res = 0;
        int len = ("" + A).length();
        int count = len-1;
        char c2 = ("" + B).charAt(0);
        System.out.println("A : " + A + " B : " + B);
            
        for(int i=A;i<=B;i++) {
            HashSet<Integer> partnerSet = new HashSet<Integer>();
            String input = "" + i;
            char c1 = input.charAt(0);
            
            for(int j=0;j<count;j++) {
                String prefix = input.substring(count-j);
                char c = prefix.charAt(0);
                if(c < c1 || c > c2) {
                    continue;
                }
                int partner = Integer.parseInt(prefix + input.substring(0, count-j));
                if(!partnerSet.contains(partner) && partner > i && partner <= B && ("" + partner).length() == len) {
                    //System.out.println("Partner Found : " + partner);
                    res++;
                    partnerSet.add(partner);
                }
            }
        }
        
        System.out.println("Num of pairs : " + res);
        
        return res;
    }
}