Java日志第52天 2020.8.28

例5.1 数组元素的引用

public class Demo5_1 {
    public static void main(String[] args) {
        int[] a = new int[10];
        for (int i = 0; i <= 9; i++) {
            a[i] = i;
        }
        for (int i = 9; i >= 0; i--) {
            System.out.print(a[i]+" ");
        }
        System.out.println();
    }
}

 

 

例5.2 用数组来处理求Fibonacci数列问题

public class Demo5_2 {
    public static void main(String[] args) {
        int[] f = new int[20];
        f[0] = 1;
        f[1] = 1;

        for (int i = 2; i < 20; i++) {
            f[i] = f[i-2]+f[i-1];

        }

        for (int i = 0; i < 20; i++) {
            if (i%5 == 0) {
                System.out.println();
            }
            System.out.print(f[i]+" ");
        }
    }
}

 

 

例5.3 编写程序，用气泡法对10个数排序

import java.util.Scanner;

public class Demo5_3 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int temp;
        int[] a = new int[11];
        System.out.print("Input 10 numbers:");
        for (int i = 1; i < 11; i++) {
            a[i] = sc.nextInt();
        }
        for (int j = 1; j <= 9; j++) {
            for (int i = 1; i <= 10-j; i++) {
                if (a[i] > a[i+1]) {
                    temp = a[i];
                    a[i] = a[i+1];
                    a[i+1] = temp;
                }
            }
        }

        System.out.println("The sorted numbers:");
        for (int i = 1; i < 11; i++) {
            System.out.print(a[i] + " ");
        }
        System.out.println();
    }
}

 

 

例5.4 将一个二维数组行和列互换，存在另一个二维数组中。

public class Demo5_4 {
    public static void main(String[] args) {
        int a[][] = new int[][] {{1, 2, 3}, {4, 5, 6}};
        int[][] b = new int[3][2];

        System.out.println("Array a:");

        for (int i = 0; i <= 1; i++) {
            for (int j = 0; j <= 2; j++) {
                System.out.print(a[i][j]+" ");
                b[j][i] = a[i][j];
            }
            System.out.println();
        }

        System.out.println("Array b:");
        for (int i = 0; i <= 2; i++) {
            for (int j = 0; j <= 1; j++) {
                System.out.print(b[i][j]+" ");
            }
            System.out.println();
        }
    }
}

 

 

 

例5.5 有一个3×4的矩阵，要求编程序求出其中值最大的那个元素的值，以及其所在的行号和列号。

public class Demo5_5 {
    public static void main(String[] args) {
        int row =0, colum=0, max;
        int[][] a = new int[][] {{5,12,23,56}, {19,28,37,46}, {-12,-34,6,8}};
        max = a[0][0];

        for (int i = 0; i <= 2; i++) {
            for (int j = 0; j <= 3; j++) {
                if (a[i][j]>max) {
                    max = a[i][j];
                    row = i+1;
                    colum = j+1;
                }
            }
        }
        System.out.println("max = "+max+", row = "+row+", colum = "+colum);
    }
}