java语言程序设计基础篇第三章编程练习题

1
套公式

2
import java.util.Scanner;
public class Main{
public static void main(String[] args){
int number1 = (int)(System.currentTimeMillis()%10);
int number2 = (int)(System.currentTimeMillis()/7%10);
int number3 = (int)(System.currentTimeMillis()/3%10);
Scanner input = new Scanner(System.in);
System.out.print("What is " + number1 + " + " + number2 + " + " + number3 + "? " );
int answer = input.nextInt();
System.out.println(number1 + " + " + number2 + " = " + answer + " is " + (number1+number2+number3 == answer));
}
}

3
参考第一章13题

4
import java.util.Scanner;
public class Main{
public static void main(String[] args){
int month;
String[] months = {"January","February","March","April","May","June","July","August",
"September","October","November","December"};
for(int i = 0; i < 20; ++i){
month = (int)(System.currentTimeMillis()%12);
System.out.println(months[month]);
}
}
}

5
import java.util.Scanner;
public class Main{
public static void main(String[] args){
String[] weeks = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
Scanner input = new Scanner(System.in);
int num1 = input.nextInt();
int num2 = input.nextInt();
int result = (num1+num2)%7;
System.out.println(weeks[result]);
}
}

6
略

7
程序清单2-10加个判断就可以了

8
import java.util.Scanner;
public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int num1 = input.nextInt();
int num2 = input.nextInt();
int num3 = input.nextInt();
int temp = 0;
if(num1 > num2){
temp = num1;
num1 = num2;
num2 = temp;
}

if(num1 > num3){
temp = num1;
num1 = num3;
num3 = temp;
}

if(num2 > num3){
temp = num2;
num2 = num3;
num3 = temp;
}

System.out.println(num1+ " " + num2 + " " +num3);
}
}

9
import java.util.Scanner;
public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
String nums = input.next();
int result = 0;
for(int i = 0; i < 9; ++i){
int num = (int)(nums.charAt(i) - '0');
result += num*(i+1);
}
result %= 11;
System.out.print(nums);
if(result == 10)
System.out.println("X");
else
System.out.println(result);
}
}

10

import java.util.Scanner;

public class Main{
public static void main(String[] args){
int number1 = (int)(Math.random()*100);
int number2 = (int)(Math.random()*100);
System.out.println("What is " + number1 + " + " + number2 + "?");
Scanner input = new Scanner(System.in);
int answer = input.nextInt();
if(number1 + number2 == answer)
System.out.print("You are correct!");
else
System.out.println(number1 + " + " + number2 + " should be " + (number1 + number2));

}
}

11

import java.util.Scanner;

public class Main{
public static void main(String[] args){
int[] months = {0,31,28,31,30,31,30,31,31,30,31,30,31};
int year = 0;
int month = 0;
Scanner input = new Scanner(System.in);
year = input.nextInt();
month = input.nextInt();
if(month == 2){
if((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))
System.out.println(months[month]+1);
else
System.out.println(months[month]);
}
else{
System.out.println(months[month]);
}
}
}

12

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
System.out.println("Enter a three-digit integer:");
int number = input.nextInt();
if(number/100 == number%10)
System.out.println(number + " is a palindrome");
else
System.out.println(number + " is not a palindrome");
}
}

13

。。。。。

14

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int number = ((int)(Math.random()*100)) % 2;
System.out.println("Please enter 0(contrary) or 1(front)");
int answer = input.nextInt();
if(number == answer)
System.out.println("You are correct");
else
System.out.println("You are wrong!");
}
}

15

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int lottery = (int)(Math.random()*1000);
System.out.println("Enter your lottery pick(three digit)");
int guess = input.nextInt();
int lottery1 = lottery/100;
int lottery2 = lottery%10;
int lottery3 = (lottery%100)/10;

int guess1 = guess/100;
int guess2 = guess%10;
int guess3 = (guess%100)/10;

if(guess == lottery)
System.out.println("Exact macth:you win $10000");
else if((lottery1 == guess2 && lottery2 == guess1 && lottery3 == guess3)||
(lottery1 == guess3 && lottery3 == guess1 && lottery2 == guess2)||
(lottery1 == guess1 && lottery2 == guess3 && lottery3 == guess2))
System.out.println("Match all digits:you win $3000");
else if(guess1 == lottery1 || guess1 == lottery2 || guess1 == lottery3 ||
guess2 == lottery1 || guess2 == lottery2 || guess2 == lottery3 ||
guess3 == lottery1 || guess3 == lottery2 || guess3 == lottery3 )
System.out.println("Match one digit:you win $1000");
else
System.out.println("Sorry,you are wrong!");
}
}

16

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int height = (int)(Math.random()*101);
int width = (int)(Math.random()*51);
if(((int)(Math.random()))%2 == 0)
height = -height;
if(((int)(Math.random()))%2 != 0)
width = -width;
System.out.println("x:" + width + ",y:"+height);
}
}

17

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
System.out.println("scissor(0),rock(1),paper(2)");
int user = input.nextInt();
int computer = (int)(System.currentTimeMillis())%3;
if(user == 0 && computer == 1)
System.out.println("You lost!");
else if(user == 0 && computer == 2)
System.out.println("You won!");
else if(user == 1 && computer == 0)
System.out.println("You won!");
else if(user == 1 && computer == 2)
System.out.println("You lost!");
else if(user == 2 && computer == 0)
System.out.println("You lost!");
else if(user == 2 && computer == 1)
System.out.println("You won!");
else
System.out.println("It is draw!");
}
}

18

套公式

19

import java.util.Scanner;

public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
double e1 = input.nextDouble();
double e2 = input.nextDouble();
double e3 = input.nextDouble();
if(e1+e2 > e3 && e1+e3 > e2 && e2+e3 > e1){
double p = (e1+e2+e3)/2;
System.out.println(Math.sqrt(p*(p-e1)*(p-e2)*(p-e3)));
}
else{
System.out.println("The length is illegal");
}
}
}

20

。。。。。。

21

/*书中给出的名字叫泽勒一致性，这个公式也叫蔡勒公式*/
import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String[] week = {"Saturday","Sunday","Monday","Tuesday","Wednesday","Thursday","Friday"};
System.out.print("Enter year:");
int year = input.nextInt();
System.out.print("Enter month 1-12:");
int month = input.nextInt();
System.out.print("Enter the day of the month:");
int day = input.nextInt();
int m = 0;
if(month == 1 || month == 2){
m = month+12;
--year;
}
else
m = month;
int k = year%100;
int j = year/100;
int h = (day + 26*(m+1)/10 + k + k/4 + j/4 + 5*j) % 7;
System.out.println(week[h]);
}

}

22

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter a point with two coordinates:");
double x = input.nextDouble();
double y = input.nextDouble();
double r = Math.sqrt(x*x + y*y);
if(r <= 10)
System.out.println("Point (" + x + "," + y + ") is in the circle.");
else
System.out.println("Point (" + x + "," + y  + ") is not in the circle.");
}

}

23

import java.util.Scanner;
public class Main {

public static void main(String[] args){
Scanner cin = new Scanner(System.in);
int x,y;
System.out.print("Enter a point with two coordinates:");
x = cin.nextInt();
y = cin.nextInt();
boolean flag = false;
if(x <= 5 && (float)y <= 2.5f) flag = true;
if(flag){
System.out.println("Point" + "(" + x + "," + y + ")" + "is in the rectangular");
}
else{
System.out.println("Point" + "(" + x + "," + y + ")" + "is not in the rectangular");
}
}
}

24

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
String[] size = {"Ace","2","3","4","5","6","7","8","9","10","Jack","Queen","King"};
String[] flowerColor = {"Clubs","Diamonds","Hearts","Spades"};
System.out.println("The card you picked is " + size[(int)(Math.random()*13)] +
" of " + flowerColor[(int)(Math.random()*4)]);
}
}

25
套公式，没啥意义

26

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter an integer:");
int number = input.nextInt();
System.out.println("Is 10 divisible by 5 and 6 ?" +
((number%5==0) && (number%6==0)));
System.out.println("Is 10 divisible by 5 or 6 ?" +
((number%5==0) || (number%6==0)));
System.out.println("Is 10 divisible by 5 or 6, but not both ?" +
((number%5==0) ^ (number%6==0)));
}
}

27

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter a point's x- and y-coordinates:");
double x = input.nextDouble();
double y = input.nextDouble();
double k = -0.5;
if(x < 0 || y < 0)
System.out.println("The point is not in the triangle.");
else{
double cx = 200 - 2*y;
if(x > cx)
System.out.println("The point is not in the triangle.");
else
System.out.println("The point is in the triangle.");
}
}
}

28
import java.util.Scanner;
public class Main {

public static void main(String[] args){
Scanner cin = new Scanner(System.in);
double r1x,r1y,r1width,r1height;
double r2x,r2y,r2width,r2height;
System.out.print("Enter r1's center x-,y-coordinates,width, and height:");
r1x = cin.nextDouble();
r1y = cin.nextDouble();
r1width = cin.nextDouble();
r1height = cin.nextDouble();
System.out.print("Enter r2's center x-,y-coordinates,width, and height:");
r2x = cin.nextDouble();
r2y = cin.nextDouble();
r2width = cin.nextDouble();
r2height = cin.nextDouble();

double distance = Math.sqrt((r1x - r2x)*(r1x - r2x) + (r1y - r2y)*(r1y - r2y));
if((distance <= r1width - r2width/2) && (distance <= r1height - r2height/2)){
System.out.println("r2 is inside r1");
}
else if((distance > r1width - r2width/2) && (distance > r1height - r2height/2)){
System.out.println("r2 does not overlap r1");
}
else{
System.out.println("r2 overlaps r1");
}
}
}

29

同上

30

参考编程练习题2.8

31

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter the exchange rate from dollars to RMB:");
double rate = input.nextDouble();
System.out.println("Enter 0 to convert dollars to RMB and 1 vice versa:");
int tmp = input.nextInt();
if(tmp == 0){
System.out.println("Enter the dollar amount:");
double dollar = input.nextDouble();
System.out.println("$" + dollar + " is " + dollar*rate + " yuan.");
}
else{
System.out.println("Enter the RMB amount:");
double RMB = input.nextDouble();
System.out.println(RMB + " yuan is $" + RMB/rate);
}
}
}

32

套公式

33

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter weight and price for package 1:");
double weight1 = input.nextDouble();
double price1 = input.nextDouble();
System.out.print("Enter weight and price for package 2:");
double weight2 = input.nextDouble();
double price2 = input.nextDouble();
double ave1 = price1/weight1;
double ave2 = price2/weight2;
if(ave1 > ave2)
System.out.println("Package 2 has a better price.");
else if(ave1 < ave2)
System.out.println("Package 1 has a better price.");
else
System.out.println("Two package have the same price.");
}
}

34

参考编程练习题3.32