mystery.java

该程序用于输出所谓的“魔幻矩阵”——即用户输入所需要矩阵的行数（前提为奇数

package mystery;
import java.io.*;
/*该程序用于输出所谓的“魔幻矩阵”——即用户输入所需要矩阵的行数（前提为奇数，否则程序发送错
 *误信息提醒用户输入正确数据），然后程序输出每行，每列以及对角线上的各数之和为同一个数。*/
public class Mystery {
  public static void main(String[] args) throws IOException {
    System.out.println("***************欢迎进入魔幻矩阵世界***************");
    System.out.println("请输入一个奇数：");
    String x;
    int i = 0, j, n;
    BufferedReader key = new BufferedReader(new InputStreamReader(System.in));
    x = key.readLine();
    n = Integer.parseInt(x);
    if (n % 2 == 0) {
      System.out.println("Error! Please enter an odd integer! Reenter");
      x = key.readLine();
      n = Integer.parseInt(x);
    }
    int[][] a = new int[n][n];
    i = 0;
    j = (n - 1) / 2;
    a[i][j] = 1;
    for (int k = 2; k <= n * n; k++) {
      i--;
      j--;
      if (i == -1 && j == -1) {
        i = 1;
        j = 0;
      }
      if (i == -1) {
        i = n + i;
      }
      if (j == -1) {
        j = n + j;
      }
      if (a[i][j] != 0) {
        i += 2;
        j++;
      }
      a[i][j] = k;
    }
    for (i = 0; i < n; i++) {
      for (j = 0; j < n; j++) {
        if (a[i][j] >= 100) {
          System.out.print(" " + a[i][j]);
        }
        else if (a[i][j] >= 10) {
          System.out.print("  " + a[i][j]);
        }
        else {
          System.out.print("   " + a[i][j]);
        }
      }
      System.out.println();
    }
  }
}