《Java语言程序设计与数据结构》编程练习答案（第五章）（一）
英文名：Introduction to Java Programming and Data Structures, Comprehensive Version, 11th Edition
5.1
import java.util.Scanner;
public class book {
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.print("Enter an integer, the input ends if it is 0: ");
int pos = 0;
int neg = 0;
double sum = 0;
int amo = 0;
while(true)
{
int tmp = input.nextInt();
if(tmp==0)
break;
else
{
amo++;
sum+=tmp;
if(tmp>0)
pos++;
else
neg++;
}
}
double ave = sum/amo;
if(amo==0)
System.out.println("No numbers are entered except 0");
else {
System.out.println("The number of positives is " + pos);
System.out.println("The number of negatives is " + neg);
System.out.println("The total is " + sum);
System.out.println("The average is " + ave);
}
}
}
5.2
import java.util.Scanner;
public class book {
public static void main(String[] args)
{
final int NUMBER_OF_QUESTIONS=10;
int correctCount = 0;
int count = 0;
long startTime = System.currentTimeMillis();
String output="";
Scanner input = new Scanner(System.in);
while(count<NUMBER_OF_QUESTIONS)
{
int number1 = (int)(Math.random()*15);
int number2 = (int)(Math.random()*15);
System.out.print("What is "+number1+" + "+number2+"? ");
int answer = input.nextInt();
if(number1+number2==answer)
{
System.out.println("You are correct!");
correctCount++;
}
else
System.out.println("Your answer is wrong.\n"+number1+" + "+number2+" should be "+(number1+number2));
count++;
output+="\n"+number1+"+"+number2+"="+answer+((number1+number2==answer)?" correct":" wrong");
}
long endTime = System.currentTimeMillis();
long testTime = endTime-startTime;
System.out.println("Correct count is "+correctCount+"\nTest time is "+testTime/100+" seconds\n"+output);
}
}
5.3
public class book {
public static void main(String[] args)
{
System.out.println("千克 磅");
for(int i=1;i<=100;i++)
System.out.printf("%-6d%8.1f\n",i*2-1,(2*i-1)*2.2);
}
}
5.4
public class book {
public static void main(String[] args)
{
System.out.println("英里 千米");
for(int i=1;i<=10;i++)
System.out.printf("%-11d%-6.3f\n",i,i*1.609);
}
}
5.5
public class book {
public static void main(String[] args)
{
System.out.println("千克 磅 磅 千克");
for(int i=1;i<=100;i++)
System.out.printf("%-5d%8.1f %-4d%8.2f\n",2*i-1,(2*i-1)*2.2,5*i+15,(5*i+15)/2.2);
}
}
5.6
public class book {
public static void main(String[] args)
{
System.out.println("英里 千米 千米 英里");
for(int i=1;i<=10;i++)
System.out.printf("%-8d%-7.3f %-8d%-6.3f\n",i,i*1.609,5*i+15,(5*i+15)/1.609);
}
}
5.7
public class book {
public static void main(String[] args)
{
double ass = 10000;
for(int i=0;i<10;i++)
ass*=(1+0.05);
double oldAss = ass;
double sum = 0;
for(int i=0;i<4;i++)
{
sum+=ass;
ass*=(1+0.05);
}
System.out.printf("Ass after 10 years is %.2f\n",oldAss);
System.out.printf("The total cost of 4 asses is %.2f\n",sum);
}
}
5.8
import java.util.Scanner;
public class book {
public static void main(String[] args)
{
System.out.println("Enter the number of girls: ");
Scanner input = new Scanner(System.in);
int num = input.nextInt();
String name = "";
double cup = 0;
for(int i=0;i<num;i++)
{
String tname = input.next();
double tmp = input.nextDouble();
if(tmp>cup)
{
cup=tmp;
name=tname;
}
}
System.out.println("The hottest girl is "+name);
}
}
5.9
import java.util.Scanner;
public class book {
public static void main(String[] args)
{
System.out.print("Enter the number of girls: ");
Scanner input = new Scanner(System.in);
int num = input.nextInt();
String name = "";
String name2 = "";
double cup = 0;
double cup2 = 0;
for(int i=0;i<num;i++)
{
String tname = input.next();
double tmp = input.nextDouble();
if(tmp>cup)
{
cup2=cup;
name2 = name;
cup=tmp;
name=tname;
}
else if(tmp>cup2)
{
cup2=tmp;
name2=tname;
}
}
System.out.println("The hottest girl is "+name);
System.out.println("The second hottest girl is "+name2);
}
}
5.10
public class book {
public static void main(String[] args)
{
int count=0;
int base = 0;
for(int i=100;i<=1000;i++)
{
if(i%5==0&&i%6==0)
{
count++;
System.out.print(i+" ");
}
if(count%10==0&&count!=base) {
System.out.print("\n");
base+=10;
}
}
}
}
5.11
public class book {
public static void main(String[] args)
{
int count=0;
int base = 0;
for(int i=100;i<=1000;i++)
{
if(i%5==0^i%6==0)
{
count++;
System.out.print(i+" ");
}
if(count%10==0&&count!=base) {
System.out.print("\n");
base+=10;
}
}
}
}
5.12
public class book {
public static void main(String[] args)
{
int n = 0;
while(n*n<12000)
n++;
System.out.println("The n is "+n);
}
}
5.13
public class book {
public static void main(String[] args)
{
int n = 0;
while(n*n*n<12000)
n++;
System.out.println("The n is "+(n-1));
}
}
