************Спираль*********** http://acmp.ru/index.asp?main=task&id_task=196

spiral_rude.java

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

public class Main{ 
    
  public static void main(String[] argv) throws IOException,Exception{
    new Main().run();
  }
 
  public static StreamTokenizer sc ; 
  public static int nextInt() throws Exception{ 
    sc.nextToken(); 
    return (int)sc.nval; 
  } 

  public void run() throws IOException,Exception{
    sc = new StreamTokenizer(new BufferedReader(new FileReader("input.txt")));   
    int n = nextInt(); 
    char[] directions =  {'r', 'd', 'l', 'u' };
    char direction = directions[0];
    int[][] arr = new int[n][n];
    arr[0][0] = 1;
    int x = 1;
    int y = 0;
    Boolean cont = true;
    int count = 2;
    int k = 0;
    PrintWriter pw = new PrintWriter(new File("output.txt"));
    if (n == 1) {
        pw.print(1);
        pw.close();
        System.exit(0);
    }
    
    while(cont) {
        switch (direction) {
            case 'r':
                for (int i = x; i < n; i++) {
                    if (arr[y][i] == 0) {
                        arr[y][i] = count++;
                        if (x+1 < n && arr[y][x+1] == 0) {
                            x++;
                        }
                    }else {
                        break;
                    }
                   
                }
                if (y+1 < n) {
                    y++;
                }
                break;
            case 'd':
                for (int i = y; i < n; i++) {
                    if (arr[i][x] == 0) {
                        arr[i][x] = count++;
                        if (y +1 < n && arr[y+1][x] == 0) {
                            y++;
                        }
                    }else {
                        break;
                    }
                   
                } 
                if (x-1 >= 0) {
                    x--;
                }
                break;
            case 'l':
                for (int i=x; i >= 0; i--) {
                    if (arr[y][i] == 0) {
                        arr[y][i] = count++;
                        if (x-1 >= 0 && arr[y][x-1] == 0) {
                            x--;
                        }
                    }else {
                        break;
                    }
                    
                }
                
                if (y-1 >= 0) {
                    y--;
                }
                break;
            case 'u':
                for (int i=y; i >= 0; i--) {
                    if (arr[i][x] == 0) {
                        arr[i][x] = count++;
                        if (y -1 >= 0 && arr[y-1][x] == 0) {
                            y--;
                        }
                    }else {
                        break;
                    }
                }
                
                if (x + 1 < n) {
                    x++;
                }
                break;
            default:
                throw new AssertionError();
        }
        
        if (arr[y][x] != 0) {
            cont = false;
        }
        k++;
        direction = directions[k % directions.length];  
    }
    
    for (int[] row : arr) {
      for (int elem : row) {
        pw.printf("%6d", elem);
      }
      pw.println();
    }
    pw.close();
  }
//   public static int[][] getSpiralArray(int dimension) {
//    int[][] spiralArray = new int[dimension][dimension];
// 
//    int numConcentricSquares = (int) Math.ceil((dimension) / 2.0);
// 
//    int j;
//    int sideLen = dimension;
//    int currNum = 1;
// 
//    for (int i = 0; i < numConcentricSquares; i++) {
//      // do top side
//      for (j = 0; j < sideLen; j++) {
//        spiralArray[i][i + j] = currNum++;
//      }
// 
//      // do right side
//      for (j = 1; j < sideLen; j++) {
//        spiralArray[i + j][dimension - 1 - i] = currNum++;
//      }
// 
//      // do bottom side
//      for (j = sideLen - 2; j > -1; j--) {
//        spiralArray[dimension - 1 - i][i + j] = currNum++;
//      }
// 
//      // do left side
//      for (j = sideLen - 2; j > 0; j--) {
//        spiralArray[i + j][i] = currNum++;
//      }
// 
//      sideLen -= 2;
//    }
// 
//    return spiralArray;
//  }
// 
//  public static void print2dArray(int[][] array) throws FileNotFoundException {
//    PrintWriter pw = new PrintWriter(new File("output.txt"));
//    for (int[] row : array) {
//      for (int elem : row) {
//        pw.printf("%6d", elem);
//      }
//      pw.println();
//    }
//    pw.close();
//  }
}