Java从入门到精通章节练习题——第五章

Exercise 1 数独

package chapter5;

/**
 * 数独
 */
public class Exercise1 {
   
    public static void main(String[] args) {
   
        int[][] arr = {
   {
   1, 2, 3}, {
   4, 5, 6}, {
   7, 8, 9}};
        for (int i = 0; i < 3; i++) {
   
            for (int j = 0; j < 3; j++) {
   
                System.out.print(arr[i][j]);
            }
            System.out.println();
        }
        System.out.println("对角线之和= " + (arr[0][0] + arr[1][1] + arr[2][2]));
        System.out.println("对角线之和= " + (arr[0][2] + arr[1][1] + arr[2][0]));
        System.out.println("列之和= " + (arr[0][0] + arr[1][0] + arr[2][0]));
        System.out.println("列之和= " + (arr[0][1] + arr[1][1] + arr[2][1]));
        System.out.println("列之和= " + (arr[0][2] + arr[1][2] + arr[2][2]));
        System.out.println("行之和= " + (arr[0][0] + arr[0][1] + arr[0][2]));
        System.out.println("行之和= " + (arr[1][0] + arr[1][1] + arr[1][2]));
        System.out.println("行之和= " + (arr[2][0] + arr[2][1] + arr[2][2]));
    }
}

Exercise 2 矩阵转置

package chapter5;

/**
 * 矩阵转置
 */
public class Exercise2 {
   
    public static void main(String[] args) {
   
        int[][] array = {
   {
   91, 25, 8},
                        {
   56, 14, 2},
                        {
   47, 3, 67}};
        int[][] newArray = new int[3][3];
        System.out.println("原数组");
        for (int i = 0; i < array.length; i++) {
   
            for (int j = 0; j < array.length; j++) {
   
                System.out.print(array[i][j] + " ");
            }
            System.out.println();
        }
        System.out.println("转置后数组");
        //循环的将旧数组按列的顺序取出，赋给新数组，则完成行、列转置
        for (int i = 0; i < array.length; i++) {
   
            for (int j = 0; j < array.length; j++) {
   
                newArray[i][j] = array[j][i];//行与列交换就是i与j的交换
                System.out.print(newArray[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Exercise 3 杨辉三角

package chapter5;

/**
 * 杨辉三角
 */
public class Exercise3 {
   
    public static void main(String[] args) {
   
        //思路:1.每行的第一个和最后一个数都为1;
        //     2.其他数为上一行相同位置的数与它前一个数的和