Java、拉丁方阵

        拉丁方阵是一个n*n的数组，其中有n个不同的拉丁字母，并且每个拉丁字母恰好只在每行和每列中出现一次。编写一个程序，提示用户输入数字n和字符数组，如示例输出所示，检测该输出数组是否是一个拉丁方阵。字符是从A开始的前面n个字符。

package pack2;import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.Set;public class LatinSquare {public static void main(String[] args) {showLatinSquare();}//	A B C D
//	B A D C
//	C D B A
//	D C A Bpublic static void showLatinSquare() {try(Scanner input = new Scanner(System.in);) {System.out.print("Enter number n: ");int n = input.nextInt();char[][] array = new char[n][n];System.out.println("Enter " + n + " rows of letters separated by spaces: ");try {inputData(input, array);System.out.println("The input array is " + (isLatinSquare(array) ? "" : "not ") + "a Latin square");}catch (InputMismatchException e) {System.out.println(e.getMessage());}}}/**是拉丁正方形吗？*/public static boolean isLatinSquare(char[][] array) {Set<Character> rows = new HashSet<>(4);	//行集合Set<Character> columns = new HashSet<>(4);	//列集合for (int i = 0; i < array.length; i++) {for (int j = 0; j < array[i].length; j++) {rows.add(array[i][j]);columns.add(array[j][i]);}if(rows.size() < array.length || columns.size() < array.length)return false;	//如果行或列集合的大小小于数组长度，返回false}return true;}/**接收数据输入*/public static void inputData(Scanner input, char[][] array) {for (int i = 0; i < array.length; i++) for (int j = 0; j < array[i].length; j++) {array[i][j] = input.next().charAt(0);if(array[i][j] < 'A' || array[i][j] > (char)('A' + array.length - 1))throw new InputMismatchException("Wrong input: the letters must" + " be from A to " + ((char)('A' + array.length - 1)));}}
}