编写一个程序，读人10 个数并且显示互不相同的数（即一个数出现多次，但仅显示一次）。（提示，读人一个数，如果它是一个新数，则将它存储在数组中。如果该数已经在数组中，则忽略它。）输入之后，数组包含的都是不同的数。下面是这个程序的运行示例：

Write a program that reads in ten numbers and displays
the number of distinct numbers and the distinct numbers separated by exactly one
space (i.e., if a number appears multiple times, it is displayed only once). (Hint:
Read a number and store it to an array if it is new. If the number is already in the
array, ignore it.) After the input, the array contains the distinct numbers.

下面是参考答案代码:

// 缺陷版本
import java.util.Arrays;
import java.util.Scanner;

public class Ans7_5_page236 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter ten numbers: ");
        int[] numberList = new int[10];
        // int[] distinctList = {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1};
        int[] distinctList = new int[10];
        Arrays.fill(distinctList,-1);

        for (int i = 0; i < 10; i++)
            numberList[i] = input.nextInt();

        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10;j++) {
                if (i == numberList[j])
                    distinctList[i] = numberList[j];
            }
        }

        int count = 0;
        for (int i = 0; i < 10; i++) {
            if (distinctList[i] != -1)
                count++;
        }
        System.out.print("The number of distinct number is " + count+
                "\nThe distinct numbers are: ");

        for (int i = 0; i < 10; i++) {
            if (distinctList[i] != -1) {
                System.out.print(distinctList[i] + " ");
            }
        }
    }
}

// 完善版本
import java.util.Arrays;
import java.util.Scanner;

public class Ans7_5_page236 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter ten numbers: ");
        int[] numberList = new int[10];

        int maxInt = -99;
        for (int i = 0; i < 10; i++) {
            numberList[i] = input.nextInt();
            if (numberList[i] > maxInt)
                maxInt = numberList[i];
        }

        int[] distinctList = new int[maxInt];
        Arrays.fill(distinctList, -99);

        int disNum = 0;
        for (int i = 0; i < maxInt; i++) {
            for (int j = 0; j < 10; j++) {
                if (i == numberList[j])
                    distinctList[i] = numberList[j];
                else if (distinctList[i] != -99)
                    disNum = distinctList[i];
            }
        }

        int count = 0;
        for (int i = 0; i < maxInt; i++) {
            if (distinctList[i] != -99) {
                count++;
            }
        }
        System.out.print("The number of distinct number is " + disNum +
                "\nThe distinct numbers are: ");

        for (int i = 0; i < maxInt; i++) {
            if (distinctList[i] != -99) {
                System.out.print(distinctList[i] + " ");
            }
        }
        System.out.print(maxInt);
    }
}

//        Enter ten numbers: 1 2 3 2 1 6 3 4 5 2
//        The number of distinct number is 5
//        The distinct numbers are: 1 2 3 4 5 6

//        Enter ten numbers: 11 22 33 22 11 66 33 44 55 67
//        The number of distinct number is 66
//        The distinct numbers are: 11 22 33 44 55 66 67

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版）

发布在博客：(https://cn.fankuiba.com)

编写一个程序，读人个数不确定的考试分数，并且判断有多少个分数是大于或等于平均分，多少个分数是低于平均分的。输人一个负数表示输入的结束。假设最高分为100。

Write a program that reads an unspecified number of scores and
determines how many scores are above or equal to the average and how many
scores are below the average. Enter a negative number to signify the end of the
input. Assume that the maximum number of scores is 100.

下面是参考答案代码:

// https://cn.fankuiba.com
import java.util.Scanner;

public class Ans7_4_page236 {
    public static void main(String[] args) {
        double[] scoreList = new double[100];
        Scanner input = new Scanner(System.in);
        System.out.print("Enter scores: (negative number signifies end): ");
        int count= 0;double score;
        do {
            score = input.nextDouble();
            scoreList[count] = score;
            count++;
        }while (score >= 0);

        double average,sum = 0;
        for (int i = 0; i < count-1; i++)
            sum += scoreList[i];

        average = sum / (count - 1);
        System.out.println("Average of scores: "+average);
        int minAverge = 0;
        int maxAverge = 0;
        for (int i = 0; i < count-1; i++) {
            if (scoreList[i] >= average)
                minAverge++;
            else
                maxAverge++;
        }
        System.out.println("Number of scores above or equal to average: " +minAverge+
                "\n"+"Number of scores below average: "+(maxAverge));
    }
}

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版）

发布在博客：(https://cn.fankuiba.com)

编写程序，读取在1到100 之间的整数，然后计算每个数出现的次数。假定输入是以0 结束的。

下面是这个程序的一个运行示例：

Write a program that reads the integers between 1and 100 and counts the occurrences of each. Assume the input ends with 0.Note that if a number occurs more than one time, the plural word “times” is used

in the output.

Enter the integers between 1 and 100: 2 5 6 5 4 3 23 43 2 0
2 occurs 2 times
3 occurs 1 time
4 occurs 1 time
5 occurs 2 times
6 occurs 1 time
23 occurs 1 time
43 occurs 1 time

下面是参考答案代码:

// https://cn.fankuiba.com
import java.util.Scanner;

public class Ans7_3_page236 {
    public static void main(String[] args) {
        int[] number = new int [101];
        Scanner input = new Scanner(System.in);
        int num;
        System.out.print("Enter the integers between 1 and 100: ");
        do {
            num = input.nextInt();
            number[num] = number[num] + 1;
        }
        while (num != 0);
        for (int i = 1; i < number.length; i++) {
            if (number[i] == 1) {
                System.out.println(i + " occurs " + number[i] + " time");
            }else if (number[i] > 1)
                System.out.println(i + " occurs " + number[i] + " times");
        }
    }
}

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版）

发布在博客：(https://cn.fankuiba.com)

编写程序，读取10 个整数，然后按照和读入顺序相反的顺序将它们显示出来。

Write a program that reads ten integers and displays
them in the reverse of the order in which they were read.

// https://cn.fankuiba.com
import java.util.Scanner;

public class Ans7_2_page236 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter 10 integers: ");
        int[] number = new int[10];
        for (int i = 0; i < 10; i++) {
            number[i] = input.nextInt();
        }
        for (int i = 9; i >= 0; i--)
            System.out.print(number[i]+" ");
    }
}

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版）

发布在博客：(https://cn.fankuiba.com)

(指定等级）编写一个程序，读入学生成绩，获取最髙分best, 然后根据下面的规则陚等级值

• 如果分数>=best-10, 等级为A

• 如果分数>=best-20, 等级为B

• 如果分数>=best-30, 等级为C

• 如果分数>=best-40, 等级为D

• 其他情况下，等级为F

程序提示用户输入学生总数，然后提示用户输入所有的分数，最后显示等级得出结论。下面

是一个运行示例：

Enter the number of students: 4
Enter 4 scores: 40 55 70 58
Student 0 score is 40 and grade is C
Student 1 score is 55 and grade is B
Student 2 score is 70 and grade is A
Student 3 score is 58 and grade is B

下面是参考答案代码:

// https://cn.fankuiba.com
import java.util.Arrays;
import java.util.Scanner;


public class Ans7_1_page235 {
    public static void main(String[] args) {
        String[] grade = {"A","B","C","D","F"};
        Scanner input = new Scanner(System.in);
        System.out.print("Enter the number of students: ");
        int number = input.nextInt();
        System.out.print("Enter " + number + " scores: ");

        int[] score = new int[number];
        for (int i = 0; i < number; i++)
            score[i] = input.nextInt();

        int[] scoreSort = new int[number];
        System.arraycopy(score,0,scoreSort,0,score.length);

        Arrays.sort(scoreSort);

        int maxSort = scoreSort[number-1];
        for (int i = 0; i < number; i++) {
            if (score[i] >= maxSort-10)
                System.out.println("Student " + i + " score is " + score[i] +
                        " and grade is " + grade[0]);
            else if (score[i] >= maxSort-20)
                System.out.println("Student " + i + " score is " + score[i] +
                        " and grade is " + grade[1]);
            else if (score[i] >= maxSort-30)
                System.out.println("Student " + i + " score is " + score[i] +
                        " and grade is " + grade[2]);
            else if (score[i] >= maxSort-40)
                System.out.println("Student " + i + " score is " + score[i] +
                        " and grade is " + grade[3]);
            else
                System.out.println("Student " + i + " score is " + score[i] +
                        " and grade is " + grade[4]);
        }
    }
}

适用Java语言程序设计与数据结构（基础篇）（原书第11版）Java语言程序设计（基础篇）（原书第10/11版）

发布在博客：(https://cn.fankuiba.com)