Java基础00-基础知识练习12

1. 减肥计划

1.1 if语句实现

import java.util.Scanner;

public class Demo01 {
    public static void main(String[] args) {
        //键盘录入一个星期数，用一个变量接收
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入一个星期数：");
        int week = sc.nextInt();
        //对星期数进行判断，这里用 if 语句实现
        if (week < 1 || week > 7) {
            System.out.println("你输入的星期数有误");
        } else if (week == 1) {
            System.out.println("跑步");
        } else if (week == 2) {
            System.out.println("游泳");
        } else if (week == 3) {
            System.out.println("慢走");
        } else if (week == 4) {
            System.out.println("动感单车");
        } else if (week == 5) {
            System.out.println("拳击");
        } else if (week == 6) {
            System.out.println("爬山");
        } else {
            System.out.println("好好吃一顿");
        }
    }
}    

输出：

1.2 switch语句实现

import java.util.Scanner;

public class Demo02 {
    public static void main(String[] args) {
        //键盘录入一个星期数，用一个变量接收
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入一个星期数：");
        int week = sc.nextInt();
        //对星期数进行判断，这里用 switch 语句实现
        switch (week) {
            case 1:
                System.out.println("跑步");
                break;
            case 2:
                System.out.println("游泳");
                break;
            case 3:
                System.out.println("慢走");
                break;
            case 4:
                System.out.println("动感单车");
                break;
            case 5:
                System.out.println("拳击");
                break;
            case 6:
                System.out.println("爬山");
                break;
            case 7:
                System.out.println("好好吃一顿");
                break;
            default:
                System.out.println("你输入的星期数有误");
        }
    }
}

2.逢7过

public class Demo03 {
    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            if ((i % 7 == 0) || (i / 10 == 7) || (i % 10 == 7)) {
                System.out.println(i);
            }
        }
    }
}

输出：

3. 不死神兔

public class Demo04 {
    public static void main(String[] args) {
        int[] arr = new int[20];

        arr[0] = 1;
        arr[1] = 1;
        // 1 1 2 3 5 8
        for (int i = 2; i < arr.length; i++) {
            arr[i] = arr[i - 2] + arr[i - 1];
        }
　　　//输出数组中最后一个元素的值，就是第20个月的兔子对数
　　　System.out.println("第二十个月兔子的对数是：" + arr[19]);
    }
}

输出：

4. 百钱百鸡

public class Demo05 {
    public static void main(String[] args) {
        int gong,mu,xiao;
//        第1层循环，用于表示鸡翁的范围
        for(gong=0;gong<=20;gong++) {
//            第2层循环，用于表示鸡母的范围
            for(mu=0;mu<=33;mu++) {
//                用于表示鸡雏的变量
                xiao=100-gong-mu;
                if (xiao%3==0&&gong*5+mu*3+xiao/3==100) {
                    System.out.println("公鸡"+gong+",母鸡"+mu+",小鸡"+xiao);
                }
            }
        }
    }
}

输出：

5. 数组元素求和

public class Demo06 {
    public static void main(String[] args) {
        int arr[]={68,27,95,88,171,996,51,210};
        int sum=0;
        for (int i = 0; i < arr.length; i++) {
            if (arr[i]%2==0&&arr[i]%10!=7&&arr[i]/10%10!=7) {
                sum=sum+arr[i];
            }
        }
        System.out.println(sum);
    }
}

输出：

6. 数组内容相同

import java.util.Iterator;

public class Demo07 {
    public static boolean getCom(int arr1[],int arr2[]) {
//         首先比较数组长度，如果长度不相同，数组内容肯定不相同，返回false
        if (arr1.length!=arr2.length) {
            return false;
        }
//         其次遍历，比较两个数组中的每一个元素，只要有元素不相同，返回false
        for (int i = 0; i < arr1.length; i++) {
            for (int j = 0; j < arr2.length; j++) {
                if (arr1[i]!=arr2[j]) {
                    return false;
                }
            }
        }
//         最后循环遍历结束后，返回true
        return true;
    }
    public static void main(String[] args) {
        int arr1[]= {10,20,30};
        int arr2[]= {10,20,30,40};
        boolean re=getCom(arr1,arr2);
        System.out.println(re);
    }
}

输出：

7. 查找

import java.util.Scanner;

public class Demo08 {
    public static int getCha(int arr[], int num) {
        int index=-1;
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == num) {
                index=1;
                return index;
            }
        }
        return index;
    }

    public static void main(String[] args) {

        int arr[] = { 19, 28, 37, 46, 50 };

        Scanner scanner = new Scanner(System.in);
        System.out.println("录入一个数据");
        int num = scanner.nextInt();

        int index = getCha(arr, num);
        System.out.println(index);
    }
}

输出：

8. 反转

public class Demo09 {
    public static void getFan(int arr[]) {
        int temp;
//            循环遍历数组，这一次初始化语句定义两个索引变量，判断条件是开始索引小于等于结束索引
        for (int start = 0, end = arr.length - 1; start <= end; start++, end--) {
            temp = arr[start];
            arr[start] = arr[end];
            arr[end] = temp;
        }
    }

    public static void getShu(int arr[]) {
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + ",");
        }
    }

    public static void main(String[] args) {
        int arr[] = { 19, 28, 37, 46, 50 };
        System.out.print("原数组:");
        getShu(arr);

        System.out.print("\n反转后数组:");
        getFan(arr);
        getShu(arr);

    }
}

输出：

9. 评委打分

public class Demo10 {

    private static double getMin(double[] arr) {
        double min = arr[0];
        for (int i = 1; i < arr.length; i++) {
            if (min > arr[i]) {
                min = arr[i];
            }
        }
        return min;
    }

    private static double getMax(double[] arr) {
        double max = arr[0];
        for (int i = 1; i < arr.length; i++) {
            if (max < arr[i]) {
                max = arr[i];
            }
        }
        return max;
    }

    private static double getSum(double[] arr) {
        double sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum = sum + arr[i];
        }
        return sum;
    }

    public static void main(String[] args) {

        double arr[] = new double[6];

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入6个评委为参赛的选手打分");
        for (int i = 0; i < 6; i++) {
            System.out.println("第"+(i+1)+"位评委");
            arr[i] = scanner.nextDouble();
        }

        System.out.println("去掉一个最高分:");
        double max = getMax(arr);
        System.out.println(max);

        System.out.println("去掉一个最低分:");
        double min=getMin(arr);
        System.out.println(min);

        System.out.println("求平均分");
        double sum=getSum(arr);
        double avg=(sum-max-min)/(arr.length-2);
        System.out.println(avg);
    }
}

输出：