JAVA语言程序设计基础课后习题第六章

//exercise 6.1
package second;
import java.util.Scanner;
public class first {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter the number of students:");
        int number=in.nextInt();
        System.out.print("Enter "+number+" scores:");
        int []score=new int[number];
        getscores(score);
        int best=max(score);
        for(int i=0;i<number;i++){
            System.out.println("Student "+i+" score is "+score[i]+" and grade is "+
                    grade(score[i],best));
        }
        
    }
    
    public static void getscores(int []score){
        Scanner in=new Scanner(System.in);
        for(int i=0;i<score.length;i++){
            score[i]=in.nextInt();
        }
    }
    
    public static int max(int[] score){
        int max=score[0];
        for(int i=0;i<score.length;i++){
            if(max<score[i])
                max=score[i];
        }
        return max;
    }
    
    public static char grade(int score,int max){
        if(score>=max-10)
            return 'A';
        else if(score>=max-20)
            return     'B';
        else if(score>=max-30)
            return 'C';
        else if(score>=max-40)
            return 'D';
        else
            return 'F';
    }

}




//exercise 6.2
package second;
import java.util.Scanner;
public class second {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int []number=get();
        reverseprint(number);
    }
    
    public static int[] get(){
        Scanner in=new Scanner(System.in);
        int[] number=new int[10];
        System.out.println("input 10 number:");
        for(int i=0;i<number.length;i++){
            number[i]=in.nextInt();
        }
        return number;
    }
    
    public static void reverseprint(int[]Array){
        for(int i=Array.length-1;i>=0;i--){
            System.out.print(Array[i]+" ");
        }
    }

}





//exercise 6.3
package second;
import java.util.Scanner;
public class third {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        int[] newarray=new int[100];
        int temp;
        
        for(int i=0;i<newarray.length;i++){
            newarray[i]=0;
        }
        System.out.print("Enter the integers between 1 and 100：");
        while((temp=in.nextInt())!=0){
            newarray[temp]++;
        }
        
        resultprint(newarray);
    }
    
    public static void resultprint(int []array){
        for(int i=0;i<array.length;i++){
            if(array[i]==1)
                System.out.println(i+" occurs "+array[i]+" time");
            if(array[i]!=0&&array[i]!=1)
                System.out.println(i+" occurs "+array[i]+" times");
        }
    }

}

//exercise 6-4
package first;
import java.util.Scanner;
public class first {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        int []score=new int[100];
        int i=0,sum=0,count=0;
        System.out.print("input integer:");
        while((score[i]=in.nextInt())!=-1){
            sum+=score[i++];
            count++;
        }
        int average=sum/count;
        int big=0,small=0;
        for(int j=0;j<count;j++){
            if(score[j]<average)
                small++;
            else
                big++;
        }
        System.out.println("average is "+average);
        System.out.println("better than average is "+big);
        System.out.println("small than average is "+small);
    }

}




//exercise 6-5
package first;
import java.util.Scanner;
public class second {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter ten numbers:");
        int []integer=new int[10];
        int count=0;
        
        for(int i=0;i<10;i++){
            boolean judge=false;
            int temp=in.nextInt();
            for(int j=0;j<count;j++){
                if(temp==integer[j]){
                    judge=true;
                }
            }
            if(!judge){
                integer[count++]=temp;
            }
        }
        System.out.print("input integer:");
        for(int i=0;i<count;i++){
            System.out.print(integer[i]+" ");
        }
    }

}




//exercise 6-7
package first;
public class third {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int []counts=new int[10];
        for(int i=0;i<100;i++){
            int random=(int)(Math.random()*10);
            counts[random]++;
        }
        for(int i=0;i<10;i++){
            System.out.print(i+" ");
        }
        System.out.println();
        for(int i=0;i<10;i++){
            System.out.print(counts[i]+" ");
        }
    }

}




//exercise 6-8
package first;

public class fourth {

    /**
     * @param args
     */
    public static int average(int[]array){
        int sum=0,count=0;
        for(int i=0;i<array.length;i++){
            sum+=array[i];
            count++;
        }
        return sum/count;
    }
    public static double average(double []array){
        double sum=0;
        int count=0;
        for(int i=0;i<array.length;i++){
            sum+=array[i];
            count++;
        }
        return sum/count;
    }

}





//exercise 6-9
package first;

public class fifth {

    /**
     * @param args
     */
    public static double min(double []array){
        double min=array[0];
        for(int i=0;i<array.length;i++){
            if(min>array[i])
                min=array[i];
        }
        return min;
    }
    

}




//exercise 6-10
package first;

public class seventh {

    /**
     * @param args
     */
    public static int indexOfSmallestElement(double[] array){
        double min=array[0];
        for(int i=0;i<array.length;i++){
            if(min>array[i])
                min=array[i];
        }
        for(int i=0;i<array.length;i++){
            if(min==array[i])
                return i;
        }
        return 0;
    }

}