Poj Solution 1244

http://poj.org/problem?id=1244

//* @author popop0p0popo
import java.util.*;
import java.io.*;

public class Main{
 public static void main(String[] args) throws Exception{
  Scanner scanner=new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        int n,flag;
        String line,r;
        char c;
        int[] idx;
        while (true){
            n=scanner.nextInt();
            if (n==0){
                break;
            }
            line=scanner.next();
            r="";
            for (int i=0;i< 26 ;i++ ){
                c=(char) ('a'+i);
                idx=new int[n];
                flag=0;
                while (line.indexOf(c)!=-1){
                    idx[flag]=line.indexOf(c);
                    flag++;
                    line=line.replaceFirst(""+c,"#");
                }
                if (flag>=3){
                    if (isD(idx,flag)){
                        r=r+c;
                    }
                }
            }
            if (r.equals("")){
                System.out.println("LOOOOOOOOSER!");
            }
            else{
                System.out.println(r);
            }
        }
    }

    public static boolean isD(int[] idx,int flag){
        int a,b,c;
        int aa,bb,cc;
        int[] iidx=new int[3];
        boolean f,ff1,ff2;
        for (int i=0;i< flag-2 ;i++ ){
            for (int j=i+1;j< flag-1 ;j++ ){
                for (int k=j+1;k< flag ;k++ ){
                    a=getP(idx[i])-1;
                    b=getP(idx[j])-1;
                    c=getP(idx[k])-1;
                    aa=getL(idx[i]);
                    bb=getL(idx[j]);
                    cc=getL(idx[k]);
   if (3*(a-b)*(a-b)+(aa-bb)*(aa-bb)==3*(a-c)*(a-c)+(aa-cc)*(aa-cc)&&
      3*(c-b)*(c-b)+(cc-bb)*(cc-bb)==3*(a-c)*(a-c)+(aa-cc)*(aa-cc)){
                        return true;
                    }
                }
            }
        }
        return false;
    }

    public static int getP(int n){
        int flag=1;
        while (true){
            if (n<=(flag)*(flag+1)/2-1){
                return flag;
            }
            flag++;
        }
    }

    public static int getL(int n){
        int p=getP(n);
        int a=n-p*(p-1)/2;
        if (p%2==0){
            return 2*a-p+1;
        }
        else{
            return 2*(a-p/2);
        }
    }
}