Java初学——编程之回形数格式方阵的实现

题目

代码如下

class RectangleTest {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		System.out.println("输入一个数字");
		int len = scanner.nextInt();
		int[][] arr = new int[len][len];

		int s = len * len;
		/*
		 * k = 1:向右 k = 2:向下 k = 3:向左 k = 4:向上
		 */
		int k = 1;
		int i = 0, j = 0;
		for (int m = 1; m <= s; m++) {
			if (k == 1) {
				if (j < len && arr[i][j] == 0) { //int型默认值为0，arr[i][j] == 0避免已赋的值被覆盖
					arr[i][j++] = m;
				} else {
					k = 2;
					i++;
					j--;
					m--;
				}
			} else if (k == 2) {
				if (i < len && arr[i][j] == 0) {
					arr[i++][j] = m;
				} else {
					k = 3;
					i--;
					j--;
					m--;
				}
			} else if (k == 3) {
				if (j >= 0 && arr[i][j] == 0) {
					arr[i][j--] = m;
				} else {
					k = 4;
					i--;
					j++;
					m--;
				}
			} else if (k == 4) {
				if (i >= 0 && arr[i][j] == 0) {
					arr[i--][j] = m;
				} else {
					k = 1;
					i++;
					j++;
					m--;
				}
			}
		}

		// 遍历
		for (int m = 0; m < arr.length; m++) {
			for (int n = 0; n < arr[m].length; n++) {
				System.out.print(arr[m][n] + "\t");
			}
			System.out.println();
		}
	}
}