/*  1   2   3   4  5
 * 14  15  16  17  6
 * 13  20  19  18  7
 * 12  11  10   9  8
     4X5螺旋数组
*/
public class Helix {
    public static void main(String[] args) {
        int n = 4;
        int m = 5;
        int [][] data = new int[n][m];
        final int UP = 0;
        final int DOWN = 1;
        final int LEFT = 2;
        final int RIGHT = 3;
        int dire = RIGHT;   // 当前数字的移动方向 
        int value = 1; // 数组元素的值
        int row = 0;       // 行下标
        int col = 0;       // 列下标
        data[0][0] = 1;
        
        while (value < n*m) {
            switch(dire) {
                case RIGHT:
                    col++;        //移动到后一列
                    if (col >= m) {
                        col--;      
                        dire = DOWN;
                        continue;
                    }else if(data[row][col] != 0) { // 已赋值
                        col--;
                        dire = DOWN;
                        continue;
                    }
                    break;
                case DOWN:
                    row++;
                    if (row >= n) {
                        row--;
                        dire = LEFT;
                        continue;
                    }
                    else if(data[row][col] != 0) {
                        row--;
                        dire = LEFT;
                        continue;
                    }
                    break;
                case LEFT:
                    col--;
                    if (col < 0) {
                        col++;
                        dire = UP;
                        continue;
                    }else if(data[row][col] != 0) {
                        col--;
                        dire = UP;
                        continue;
                    }
                    break;
                case UP:
                    row--;
                    if (data[row][col] != 0) {
                        row++;
                        dire = RIGHT;
                        continue;
                    }
                    break;
            }
            value++; //数值增加1
            data[row][col] = value;//赋值   
        }
        

        for(int i = 0;i < data.length;i++){
                 for(int j = 0;j < data[i].length;j++){
                          if(data[i][j] < 10){//右对齐
                                    System.out.print(' ');
                          }
                          System.out.print(data[i][j]);
                          System.out.print(' ');
                 }
                 System.out.println();
        }
    }
}