//exercise 3.1
package thirdchapterexercise1;
import java.util.Scanner;
public class first {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in =new Scanner(System.in);
System.out.print("Enter a,b,c:");
double a=in.nextDouble();
double b=in.nextDouble();
double c=in.nextDouble();
double judge=b*b-4*a*c;
if (judge>0){
double x1=(-b+(Math.pow(judge, 0.5)))/(2*a);
double x2=(-b-(Math.pow(judge, 0.5)))/(2*a);
System.out.println("The roots are "+x1+" and "+x2);
}
else if (judge==0){
double x=(-b)/(2*a);
System.out.println("The root is "+x);
}
else
System.out.println("The equation has no real roots");
}
}
//exercise 3.2
package thirdchapterexercise1;
import java.util.Scanner;
public class second {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in =new Scanner(System.in);
System.out.print("Enter an integer:");
int integer=in.nextInt();
System.out.println("Is "+integer+" an even number?"+(integer%2==0));
}
}
//exercise 3.3
package thirdchapterexercise1;
import java.util.Scanner;
public class third {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter a,b,c,d,e,f:");
double a=in.nextDouble(),b=in.nextDouble(),c=in.nextDouble(),d=in.nextDouble();
double e=in.nextDouble(),f=in.nextDouble();
double judge=a*d-b*c;
if (judge==0){
System.out.println("The equation has no solution");
System.exit(0);
}
double x=(e*d-b*f)/judge;
double y=(a*f-e*c)/judge;
System.out.println("x is "+x+" and y is "+y);
}
}
//exercise 3.4
package thirdchapterexercise1;
import java.util.Scanner;
public class fourth {
public static void main(String[] args) {
// TODO Auto-generated method stub
int number1=(int)(Math.random()*100);
int number2=(int)(Math.random()*100);
Scanner in=new Scanner(System.in);
System.out.print("What is "+number1+" + "+number2+"?");
int input=in.nextInt();
System.out.println("Your answer is "+(number1+number2==input));
}
}
//exercise 3.5
package thirdchapterexercise1;
import java.util.Scanner;
public class fifth {
public static void main(String[] args) {
// TODO Auto-generated method stub
int number1=(int)(Math.random()*10);
int number2=(int)(Math.random()*10);
int number3=(int)(Math.random()*10);
Scanner in=new Scanner(System.in);
System.out.print("What is "+number1+" + "+number2+" + "+number3+"?");
int input =in.nextInt();
System.out.println("Your answer is "+(number1+number2+number3==input));
}
}
//exercise 3.6
package thirdchapterexercise1;
import java.util.Scanner;
public class sixth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
//input pounds
System.out.print("Enter weight in pounds:");
double weight=in.nextDouble();
//input feet
System.out.print("Enter feet:");
int feet =in.nextInt();
//input inches
System.out.print("Enter height in inches:");
int height =in.nextInt();
//The feet and inches to meter,The pounds into kilograms
double kilograms=weight*0.45359237;
double meter=height*0.0254+feet*0.3048;
//get BMI
double bmi=kilograms/Math.pow(meter, 2);
System.out.println("Your BMI is "+bmi);
//The weight classification
if(bmi<16)
System.out.println("You are seriously underweight");
else if (bmi<18)
System.out.println("You are underweight");
else if (bmi<24)
System.out.println("You are normal weight");
else if (bmi<29)
System.out.println("Yo are overweight");
else if (bmi<35)
System.out.println("You are seriously overweight");
else
System.out.println("You are gravely overweight");
}
}
//exercise 3.8
package thirdchapterexercise1;
import javax.swing.JOptionPane;
public class seventh {
public static void main(String[] args) {
// TODO Auto-generated method stub
String number1=JOptionPane.showInputDialog("input number1:");
String number2=JOptionPane.showInputDialog("input number1:");
String number3=JOptionPane.showInputDialog("input number1:");
int num1=Integer.parseInt(number1);
int num2=Integer.parseInt(number2);
int num3=Integer.parseInt(number3);
int temp;
if (num1>num2){
temp=num1;
num1=num2;
num2=temp;
}
if(num2>num3){
temp=num2;
num2=num3;
num3=temp;
}
if(num1>num2){
temp=num1;
num1=num2;
num2=temp;
}
System.out.println(num1+"\t"+num2+"\t"+num3);
}
}
//exercise 3.9
package thirdchapterexercise1;
import java.util.Scanner;
public class eighth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("input number:");
String number=in.next();
//字符串转化为字符数组
char a[]=number.toCharArray();
int b[]=new int[number.length()],sum=0;
for(int i =0;i<number.length();i++){
//将字符数组转化为数字数组
b[i]=((int)a[i]-48)*(i+1);
//sum
sum=sum+b[i];
}
int d10=sum%11;
//将数字转化为字符，
char d=(char)(d10+48);
//连接字符串
number=number+d;
System.out.println("ISBN is "+number);
}
}
//exercise 3.10
package thirdchapterexercise1;
import java.util.Scanner;
public class ninth {
public static void main(String[] args){
int number1=(int)(Math.random()*10);
int number2=(int)(Math.random()*10);
if(number1<number2){
int temp=number1;
number1=number2;
number2=temp;
}
System.out.print("What is "+number1+"+"+number2+"? ");
Scanner in=new Scanner(System.in);
int answer=in.nextInt();
if(number1+number2==answer)
System.out.println("You are correct!");
else
System.out.println("Your answer is wrong\n"+number1+"+"+number2+" sho"
+ "uld be "+(number1+number2));
}
}
//exercise 3.11
package thirdchapterexercise1;
import java.util.Scanner;
public class tenth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("please input mouth and year:");
int mouth=in.nextInt();
int year=in.nextInt();
switch(mouth){
case 1:
System.out.println("January "+year+" has 31 days");
break;
case 3:
System.out.println("March "+year+" has 31 days");
break;
case 4:
System.out.println("April"+year+" has 30 days");
break;
case 5:
System.out.println("May "+year+" has 31 days");
break;
case 6:
System.out.println("June "+year+" has 30 days");
break;
case 7:
System.out.println("July "+year+" has 31 days");
break;
case 8:
System.out.println("August "+year+" has 31 days");
break;
case 9:
System.out.println("September "+year+" has 30 days");
break;
case 10:
System.out.println("October "+year+" has 31 days");
break;
case 11:
System.out.println("November "+year+" has 30 days");
break;
case 12:
System.out.println("December "+year+" has 31 days");
break;
default:
break;
}
if(mouth==2){
if(year%4==0&&year%100!=0||year%400==0){
System.out.println("February "+year+" has 29 days");
}
else
{
System.out.println("February "+year+" has 20 days");
}
}
}
}
//exercise 3.12
package thirdchapterexercise2;
import java.util.Scanner;
public class first {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("please input a integer:");
int input=in.nextInt();
if(input%5==0&&input%6==0)
System.out.println(input+" is divisible by both 5 and 6");
else if (input %5==0^input%6==0)
System.out.println(input+" is dibisible by 5 or 6,but not both");
else
System.out.println(input+" is not divisible by either 5 or 6");
}
}
//exercise 3.14
package thirdchapterexercise2;
import java.util.Scanner;
public class second {
public static void main(String[] args) {
// TODO Auto-generated method stub
int random=(int)(Math.random()*100)%2;
String computer;
//指定random
if (random==0){
computer="tails";
}
else
computer="heads";
Scanner in=new Scanner(System.in);
System.out.println("(please input heads of tails)");
String input =in.next();
if((random==1&&input.equals("heads"))||(random==0&&input.equals("tails"))){
System.out.println("computer is "+computer);
System.out.println("You are right!");
}
else {
System.out.println("computer is "+computer);
System.out.println("You are wrong!");
}
}
}
//exercise 3.15
package thirdchapterexercise2;
import java.util.Scanner;
public class third {
public static void main(String[] args) {
// lottery number
int lottery=(int)(Math.random()*1000);
Scanner in=new Scanner(System.in);
System.out.print("Enter your lottery pick (three digits):");
int guess =in.nextInt();
//separation lottery digit
int lotteryDigit1=lottery/100;
int lotteryDigit2=lottery/10%10;
int lotteryDigit3=lottery%10;
//separation guess digit
int guessDigit1=guess/100;
int guessDigit2=guess/10%10;
int guessDigit3=guess%10;
System.out.println("The lottery number is "+lottery);
//judge
if (guess == lottery)
System.out.println("Exact match:you win $10000");
else if((guessDigit2==lotteryDigit1
||guessDigit2==lotteryDigit3)
&&(guessDigit1==lotteryDigit2
||guessDigit1==lotteryDigit3)
&&(guessDigit3==lotteryDigit1
||guessDigit3==lotteryDigit2))
System.out.println("Match all digits: you win $3000");
else if(guessDigit1==lotteryDigit1
||guessDigit1==lotteryDigit2
||guessDigit1==lotteryDigit3
||guessDigit2==lotteryDigit1
||guessDigit2==lotteryDigit2
||guessDigit2==lotteryDigit3
||guessDigit3==lotteryDigit1
||guessDigit3==lotteryDigit2
||guessDigit3==lotteryDigit3)
System.out.println("Match one digit:you win $ 1000");
else
System.out.println("Sorry,no match");
}
}
//exercise 3.16
package thirdchapterexercise2;
public class fourth {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a=(int)(Math.random()*26)+‘A‘;
char b=(char)a;
System.out.println(b);
}
}
//exercise 3.17
package thirdchapterexercise2;
import java.util.Scanner;
public class fifth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("scissor(0),rock(1),paper(2):");
int input=in.nextInt();
int computer=(int)(Math.random()*3);
if(computer==0&&input==1)
System.out.print("The computer is scissor.You are rock.You win");
else if (computer==0&&input==2)
System.out.print("The computer is scissor.You are paper.You 输了.");
else if (computer==0&&input==0)
System.out.print("The computer is scissor.You are scissor.It is a draw.");
else if (computer==1&&input==0)
System.out.print("The computer is rock.You are scissor.You 输了.");
else if (computer==1&&input==1)
System.out.print("The computer is rock.You are rock.It is a draw.");
else if (computer==1&&input==2)
System.out.print("The computer is rock.You are paper.You win.");
else if (computer==2&&input==0)
System.out.print("The computer is paper.You are scissor.You win.");
else if (computer==2&&input==1)
System.out.print("The computer is paper.You are rock.You 输了.");
else if (computer==2&&input==2)
System.out.print("The computer is paper.You are paper.It is a draw.");
}
}
//exercise 3.18
package thirdchapterexercise2;
import javax.swing.JOptionPane;
public class sixth {
public static void main(String[] args) {
// TODO Auto-generated method stub
String year=JOptionPane.showInputDialog("Enter a year:");
int year1=Integer.parseInt(year);
boolean isLeapYear=(year1%4==0&&year1%100!=0)||(year1%400==0);
JOptionPane.showMessageDialog(null,year1+"is a leap year?"+isLeapYear);
}
}
//exercise 3.19
package thirdchapterexercise2;
import java.util.Scanner;
public class seventh {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter three edges:");
double side1=in.nextDouble();
double side2=in.nextDouble();
double side3=in.nextDouble();
double max=side1,sum=0;
if(max<side2){
max=side2;
sum=sum+side1;
}
else
sum=sum+side2;
if(max<side3){
max=side3;
sum=sum+side2;
}
else
sum=sum+side3;
System.out.println("Can edges "+side1+","+side2+" and "+side3+" form a "
+ "triangle?"+(sum>max));
}
}
//exercise 3.20
package thirdchapterexercise2;
import java.util.Scanner;
public class eighth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.println("please input -58F to 41F of temperature and better than 2 of "
+ "wind speed!!");
//input Fahrenheit
System.out.print("Enter the temperature in Fahrenheit:");
double fahreheit=in.nextDouble();
if(fahreheit<-58||fahreheit>41){
System.out.println("input error!!");
System.exit(0);
}
//input wind speed
System.out.print("Enter the wind speed miles per hours:");
double windspeed=in.nextDouble();
if (windspeed<2){
System.out.println("input error!!");
System.exit(0);
}
double windchillindex=35.74+0.6215*fahreheit-35.75*Math.pow(windspeed,0.16)+
0.4275*fahreheit*Math.pow(windspeed,0.16);
System.out.print("The wind chill index is "+windchillindex);
}
}
//exercise 3.21
package thirdchapterexercise2;
import java.util.Scanner;
public class ninth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter year:(e.g.m 2008):");
int year=in.nextInt();
System.out.print("Enter month : 1-12:");
int month=in.nextInt();
System.out.print("Enter the day of the month: 1-31:");
int day=in.nextInt();
if (month==1||month==2){
month=month+12;
year--;
}
int q=(day+(26*(month+1)/10)+year%100+year%100/4+year/100/4+5*year/100)%7;
switch(q){
case 0:
System.out.println("Day of the weel is Saterday");
break;
case 1:
System.out.println("Day of the weel is Sunday");
break;
case 2:
System.out.println("Day of the weel is Monday");
break;
case 3:
System.out.println("Day of the weel is Tuesday");
break;
case 4:
System.out.println("Day of the weel is Wednesday");
break;
case 5:
System.out.println("Day of the weel is Thursday");
break;
case 6:
System.out.println("Day of the weel is Friday");
break;
}
}
}
//exercise 3.22
package thirdchapterexercise2;
import java.util.Scanner;
public class tenth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter a point with two coordinates:");
double x=in.nextDouble();
double y=in.nextDouble();
double distance=Math.pow((x*x+y*y),0.5);
if (distance<10){
System.out.print("Point("+x+","+y+") is in the circle ");
}
else
System.out.print("Point("+x+","+y+") is not in the circle ");
}
}
//exercise 3.23
package thirdchapterexercise3;
import java.util.Scanner;
public class first {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter a point with two coordinates:");
double x=in.nextDouble();
double y=in.nextDouble();
//horizontal is x
double horizontal=x;
//vertical is y
double vertical=y;
if (horizontal<5&&vertical<2.5)
System.out.print("Point("+x+","+y+") is in the rectangle");
else
System.out.print("Point("+x+","+y+") is not in the rectangle");
}
}
//exercise 3.24
package thirdchapterexercise3;
public class second {
public static void main(String[] args) {
// TODO Auto-generated method stub
int number1=(int)(Math.random()*13);
int color1=(int)(Math.random()*4);
String number=null,color=null;
switch(number1){
case 0:
number="Ace";
break;
case 1:
number="2";
break;
case 2:
number="3";
break;
case 3:
number="4";
break;
case 4:
number="5";
break;
case 5:
number="6";
break;
case 6:
number="7";
break;
case 7:
number="8";
break;
case 8:
number="9";
break;
case 9:
number="10";
break;
case 10:
number="Jack";
break;
case 11:
number="Queen";
break;
case 12:
number="King";
break;
default:
break;
}
switch(color1){
case 0:
color="Clubs";
break;
case 1:
color="Diamond";
break;
case 2:
color="Heart";
break;
case 3:
color="Spades";
break;
}
System.out.println("The card you picked is "+number+" of "+color);
}
}
//exercise 3.25
package thirdchapterexercise3;
import java.util.Scanner;
public class third {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter three edges:");
double side1=in.nextDouble();
double side2=in.nextDouble();
double side3=in.nextDouble();
double max=side1,sum=0;
//find max and sum of two side
//Judge whether existence of triangle
if(max<side2){
max=side2;
sum=sum+side1;
}
else
sum=sum+side2;
if(max<side3){
max=side3;
sum=sum+side2;
}
else
sum=sum+side3;
//calculate the perimeter
double perimeter=sum+max;
if(sum<max||sum==max)
System.out.println("input is wrong");
else
System.out.print("sum of three side is:"+perimeter);
}
}
//exercise 3.27
package thirdchapterexercise3;
import java.util.Scanner;
public class fourth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.print("Enter a point‘s x- and y-coordinates:");
double x=in.nextDouble();
double y=in.nextDouble();
double distance1=Math.pow((x*x+y*y), 0.5);
double distance2=Math.pow((x-200)*(x-200)+(y-100)*(y-100),0.5);
if(distance1>distance2||x>200||x<0||y>100||y<0)
System.out.print("The point is not in the triangle");
else
System.out.print("The point is in the triangle");
}
}
//exercise 3.28
package thirdchapterexercise3;
import java.util.Scanner;
public class fifth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in =new Scanner(System.in);
System.out.println("Enter r1‘s center x-,y-coordinates,width,and height:");
double x1=in.nextDouble();
double y1=in.nextDouble();
double w1=in.nextDouble();
double h1=in.nextDouble();
System.out.println("Enter r2‘s center x-,y-coordinates,width,and height:");
double x2=in.nextDouble();
double y2=in.nextDouble();
double w2=in.nextDouble();
double h2=in.nextDouble();
double insidelimitwidth=Math.abs(w1-w2);
double insidelimitheight=Math.abs(h1-h2);
double insidejudgewidth=Math.abs(x2-x1);
double insidejudgeheight=Math.abs(y2-y1);
double overlapslimitwidth=w1+w2;
double overlapslimitheight=h1+h2;
double overlapsjudgewidth=Math.abs(x2-x1);
double overlapsjudgeheight=Math.abs(y2-y1);
if (insidejudgewidth<insidelimitwidth&&insidejudgeheight<insidelimitheight)
System.out.println("r2 is inside r1");
else if (overlapsjudgewidth<overlapslimitwidth&&overlapsjudgeheight<overlapslimitheight)
System.out.println("r2 overlaps r1");
else
System.out.println("r2 does not overlap r1");
}
}
//exercise 3.29
package thirdchapterexercise3;
import java.util.Scanner;
public class sixth {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
System.out.println("Enter circle1‘s center x-,y-coordinates,and radius:");
double x1=in.nextDouble();
double y1=in.nextDouble();
double r1=in.nextDouble();
System.out.println("Enter circle2‘s center x-,y-coordinates,and radius:");
double x2=in.nextDouble();
double y2=in.nextDouble();
double r2=in.nextDouble();
double distance=Math.pow((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2),0.5);
double insidelimit=Math.abs(r1-r2);
double overlapslimit=r1+r2;
if(distance<insidelimit)
System.out.println("circle2 is inside circle1");
else if (distance<overlapslimit)
System.out.println("circle2 overlaps circle1");
else
System.out.println("circle2 does not overlap circle1");
}
}
时间： 2024-09-30 04:17:25