PKU Judge Online 2039 To and Fro

■2039 To and Fro

□Problem
省略．

□Solution
省略．

□Code

package p2039;

import java.util.*;
import java.lang.*;
import java.math.*;
import java.io.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

// AC
public class Main{

    Scanner sc=new Scanner(System.in);

    final int INF=Integer.MAX_VALUE;
    final double EPS=1e-9;

    void run(){
        for(;;){
            int n=sc.nextInt();
            if(n==0)
                break;
            String s=sc.next();
            int m=s.length()/n;
            for(int j=0; j<n; j++){
                for(int i=0; i<m; i++){
                    int k=j+i*n;
                    if(i%2==1)
                        k+=n-1-2*j;
                    print(""+s.charAt(k));
                }
            }
            println("");
        }
    }

    void print(String s){
        System.out.print(s);
    }

    void println(String s){
        System.out.println(s);
    }

    public static void main(String[] args){
        // System.setOut(new PrintStream(new BufferedOutputStream(System.out)));
        new Main().run();
    }
}