蛇形矩阵

是道老题了。凭着印象写，代码技巧是：先判断，后移动。

public class Snake {

    static int[][] arr;

    public static void print(int x, int y) {
        arr = new int[x][y];
        final int key = x * y;
        int i = 0;
        int j = -1;
        int cnt = 1;
        while (cnt <= key) {
            while (j + 1 < y && arr[i][j + 1] == 0) {
                arr[i][++j] = cnt++;
            }
            while (i + 1 < x && arr[i + 1][j] == 0) {
                arr[++i][j] = cnt++;
            }
            while (j - 1 >= 0 && arr[i][j - 1] == 0) {
                arr[i][--j] = cnt++;
            }
            while (i - 1 >= 0 && arr[i - 1][j] == 0) {
                arr[--i][j] = cnt++;
            }
        }

        for (int k = 0; k < arr.length; k++) {
            System.out.println(Arrays.toString(arr[k]));
        }

    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int x = scanner.nextInt();
            int y = scanner.nextInt();
            print(x, y);
        }
    }
}