Java语言程序设计基础篇编程练习题-第三章

红太狼 2022-12-05 13:50 170阅读 0赞

### 3.1（代数：解一元二次方程） ###

import java.util.Scanner;
    
    public class Test3_01 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter a, b, c: ");
    		double a = input.nextDouble();
    		double b = input.nextDouble();
    		double c = input.nextDouble();
    		input.close();
    		
    		double criterion = b * b - 4 * a * c;
    		
    		if(criterion > 0) {
        
    			double root1 = (-b + Math.pow(criterion, 0.5)) / (2 * a);
    			double root2 = (-b - Math.pow(criterion, 0.5)) / (2 * a);
    			System.out.println("The equation has two roots " + root1 + " and " + root2);
    		}else if(criterion == 0) {
        
    			double root = (-b + Math.pow(criterion, 0.5)) / (2 * a);
    			System.out.println("The equation has one root " + root);
    		}else {
        
    			System.out.println("The equation has no real roots");
    		}
    		
    	}
    }

### 3.2（游戏：三个数的加法） ###

import java.util.Scanner;
    
    public class Test3_02 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		int result = 0;
    		double num = Math.random();
    		if(num < 0.5) {
        
    			//产生两个数
    			int num1 = (int)(Math.random() * 10);
    			int num2 = (int)(Math.random() * 10);
    			System.out.print("Enter the sum of (" + num1 + " + " + num2 + ") :");
    			result = num1 + num2;
    		}else {
        
    			//产生三个数
    			int num1 = (int)(Math.random() * 10);
    			int num2 = (int)(Math.random() * 10);
    			int num3 = (int)(Math.random() * 10);
    			System.out.print("Enter the sum of (" + num1 + " + " + num2 + " + " + num3 + ") :");
    			result = num1 + num2 + num3;
    		}
    		int sum = input.nextInt();
    		input.close();
    		if(sum == result) {
        
    			System.out.println("Yes");
    		}else {
        
    			System.out.println("No");
    		}
    	}
    }

### 3.3（代数：求解2\*2线性方程） ###

import java.util.Scanner;
    
    public class Test3_03 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter a, b, c, d, e, f,: ");
    		double a = input.nextDouble();
    		double b = input.nextDouble();
    		double c = input.nextDouble();
    		double d = input.nextDouble();
    		double e = input.nextDouble();
    		double f = input.nextDouble();
    		input.close();
    		
    		double criterion = a * d - b * c;
    		
    		if(criterion == 0) {
        
    			System.out.println("The equation has no solution");
    		}else {
        
    			double x = (e * d - b * f) / (a * d - b * c);
    			double y = (a * f - e * c) / (a * d - b * c);
    			System.out.println("x is " + x + " and y is " + y);
    		}
    	}
    }

### 3.4（随机月份） ###

import java.util.Scanner;
    
    public class Test3_04 {
        
    	public static void main(String[] args) {
        
    		int month = (int)(Math.random() * 12 + 1);
    		switch(month) {
        
    		case 1:
    			System.out.println("January");
    			break;
    		case 2:
    			System.out.println("February");
    			break;
    		case 3:
    			System.out.println("March");
    			break;
    		case 4:
    			System.out.println("April");
    			break;
    		case 5:
    			System.out.println("May");
    			break;
    		case 6:
    			System.out.println("June");
    			break;
    		case 7:
    			System.out.println("July");
    			break;
    		case 8:
    			System.out.println("August");
    			break;
    		case 9:
    			System.out.println("September");
    			break;
    		case 10:
    			System.out.println("October");
    			break;
    		case 11:
    			System.out.println("November");
    			break;
    		case 12:
    			System.out.println("December");
    			break;
    		default:
    			System.out.println(month);
    		}
    	}
    }

### 3.5（找到将来的日期） ###

import java.util.Scanner;
     
    public class Test3_05 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter today's day: ");
    		int today = input.nextInt();
    		System.out.print("Enter the number of days elapsed since today: ");
    		int number = input.nextInt();
    		input.close();
    		String week = "";
    		switch(today) {
        
    		case 1:
    			week = "Monday";
    			break;
    		case 2:
    			week = "Tuesday";
    			break;
    		case 3:
    			week = "Wednesday";
    			break;
    		case 4:
    			week = "Thursday";
    			break;
    		case 5:
    			week = "Friday";
    			break;
    		case 6:
    			week = "Saturday";
    			break;
    		case 0:
    			week = "Sunday";
    			break;
    		default:
    			System.out.println("erro");
    		}
    		System.out.print("Today is " + week);
    		int next = number % 7;
    		today += next;
    		if(today > 6) {
        
    			today -= 7;
    		}
    		switch(today) {
        
    		case 1:
    			week = "Monday";
    			break;
    		case 2:
    			week = "Tuesday";
    			break;
    		case 3:
    			week = "Wednesday";
    			break;
    		case 4:
    			week = "Thursday";
    			break;
    		case 5:
    			week = "Friday";
    			break;
    		case 6:
    			week = "Saturday";
    			break;
    		case 0:
    			week = "Sunday";
    			break;
    		default:
    			System.out.println("erro");
    		}
    		System.out.println(" and the future day is " + week);
    	}
    }

### 3.6（医疗应用程序：BMI） ###

import java.util.Scanner;
    public class Test3_06 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter weight in pounds: ");
    		double weight = input.nextDouble();
    		System.out.print("Enter feet: ");//英尺
    		double feet = input.nextDouble();
    		System.out.print("Enter inches: ");//英寸    1英尺=12英寸
    		double inches = input.nextDouble();
    		input.close();
    		
    		inches += feet * 12;
    		
    		final double KILOGRAMS_PER_POUND = 0.45359237;
    		final double METERS_PER_INCH = 0.0254;
    		
    		double weightInKilograms = weight * KILOGRAMS_PER_POUND;
    		double heightInMeters = inches * METERS_PER_INCH;
    		
    		double bmi = weightInKilograms / (heightInMeters * heightInMeters);
    		
    		System.out.println("BMI is " + bmi);
    		
    		if(bmi < 18.5) {
        
    			System.out.println("Underweight");
    		}else if(bmi < 25) {
        
    			System.out.println("Normal");
    		}else if(bmi < 30) {
        
    			System.out.println("Overweight");
    		}else {
        
    			System.out.println("Obese");
    		}
    	}
    }

### 3.7（财务应用程序，整钱兑零） ###

import java.util.Scanner;
    public class Test3_07 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter an amount in double, for example 11.56: ");
    		double amount = input.nextDouble();
    		input.close();
    		
    		int remainingAmount = (int)(amount * 100);
    		
    		int numberOfOneDollars = remainingAmount / 100;
    		remainingAmount = remainingAmount % 100;
    		
    		int numberOfQuarters = remainingAmount / 25;
    		remainingAmount = remainingAmount % 25;
    		
    		int numberOfDimes = remainingAmount / 10;
    		remainingAmount = remainingAmount % 10;
    		
    		int numberOfNickels = remainingAmount / 5;
    		remainingAmount = remainingAmount % 5;
    		
    		int numberOfPennies = remainingAmount;
    		
    		System.out.println("Your amount " + amount + " consists of");
    		if(numberOfOneDollars <= 1) {
        
    			System.out.println("    " + numberOfOneDollars + " dollar");
    		}else {
        
    			System.out.println("    " + numberOfOneDollars + " dollars");
    		}
    		if(numberOfQuarters <= 1) {
        
    			System.out.println("    " + numberOfQuarters + " quarter ");
    		}else {
        
    			System.out.println("    " + numberOfQuarters + " quarters ");
    		}
    		if(numberOfDimes <= 1) {
        
    			System.out.println("    " + numberOfDimes + " dime");
    		}else {
        
    			System.out.println("    " + numberOfDimes + " dimes");
    		}
    		if(numberOfNickels <= 1) {
        
    			System.out.println("    " + numberOfNickels + " nickel");
    		}else {
        
    			System.out.println("    " + numberOfNickels + " nickels");
    		}
    		if(numberOfPennies <= 1) {
        
    			System.out.println("    " + numberOfPennies + " pennie");
    		}else {
        
    			System.out.println("    " + numberOfPennies + " pennies");
    		}
    		
    	}
    }

### 3.8（对三个整数排序） ###

import java.util.Scanner;
     
    public class Test3_08 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter a, b, c: ");
    		int a = input.nextInt();
    		int b = input.nextInt();
    		int c = input.nextInt();
    		input.close();
    		
    		if(a > b) {
        
    			int t = a;
    			a = b;
    			b = t;
    		}
    		if(a > c) {
        
    			int t = a;
    			a = c;
    			c = t;
    		}
    		if(b > c) {
        
    			int t = b;
    			b = c;
    			c = t;
    		}
    		
    		System.out.println(a + ", " + b + ", " + c);
    	}
    }

### 3.9（商业，检查ISBN-10） ###

import java.util.Scanner;
     
    public class Test3_09 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter the first 9 digits of an ISBN as integer: ");
    		String str = input.nextLine();
    		input.close();
    		
    		int sum = 0;
    		for(int i = 0; i < str.length(); i++) {
        
    			sum += (int)(str.charAt(i) - '0') * (i + 1);
    		}
    		int endNumber = sum % 11;
    		String s = "";
    		switch(endNumber) {
        
    		case 0:
    			s = "0";
    			break;
    		case 1:
    			s = "1";
    			break;
    		case 2:
    			s = "2";
    			break;
    		case 3:
    			s = "3";
    			break;
    		case 4:
    			s = "4";
    			break;
    		case 5:
    			s = "5";
    			break;
    		case 6:
    			s = "6";
    			break;
    		case 7:
    			s = "7";
    			break;
    		case 8:
    			s = "8";
    			break;
    		case 9:
    			s = "9";
    			break;
    		case 10:
    			s = "X";
    			break;
    		default:
    			break;
    		}
    		str += s;
    		System.out.println("The ISBN-10 number is " + str);
    	}
    }

### 3.10（游戏：加法检测） ###

import java.util.Scanner;
     
    public class Test3_10 {
        
    	public static void main(String[] args) {
        
     
    		int number1 = (int)(Math.random() * 100);
    		int number2 = (int)(Math.random() * 100);
     
    		System.out.print("What is " + number1 + " + " + number2 + " ? ");
    		
    		Scanner input = new Scanner(System.in);
    		int answer = input.nextInt();
    		input.close();
    		
    		if(answer == number1 + number2) {
        
    			System.out.println("You are correct!");
    		}else {
        
    			System.out.println("Your answer is wrong.");
    			System.out.println(number1 + " + " + number2 + " should be " + (number1 + number2));
    		}
    	
    	}
    }

### 3.11（） ###

如果放在第三章，单纯使用选择语句，可以使用示例代码1。但是这种题目是有使用数组解决的方法，如示例代码2所示。

// 示例代码1
    import java.util.Scanner;
     
    public class Test3_11 {
        
        public static void main(String[] args) {
        
            Scanner input = new Scanner(System.in);
            System.out.print("Enter number of years: ");
            int years = input.nextInt();
            System.out.print("Enter number of months: ");
            int months = input.nextInt();
            input.close();
            
            boolean falg = (years % 4 == 0 && years % 100 != 0) || years % 400 == 0;
            int days = 0;
            String str = "";
            
            switch(months) {
        
            case 1:
                str = "January";
                days = 31;
                break;
            case 2:
                str = ("February");
                if(falg) {
        
                    days = 29;
                }else {
        
                    days = 28;
                }
                break;
            case 3:
                str = ("March");
                days = 31;
                break;
            case 4:
                str = ("April");
                days = 30;
                break;
            case 5:
                str = ("May");
                days = 31;
                break;
            case 6:
                str = ("June");
                days = 30;
                break;
            case 7:
                str = ("July");
                days = 31;
                break;
            case 8:
                str = ("August");
                days = 31;
                break;
            case 9:
                str = ("September");
                days = 30;
                break;
            case 10:
                str = ("October");
                days = 31;
                break;
            case 11:
                str = ("November");
                days = 30;
                break;
            case 12:
                str = ("December");
                days = 31;
                break;
            default:
                System.out.println(months);
            }
            
            System.out.println(str + " " + years + " has " + days + " days");
        }
    }

// 示例代码2
    import java.util.Scanner;
     
    public class TestMonth {
        
    	public static void main(String[] args) {
        
    		String[] month = {
        "", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    		int[] days = {
        29, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter number of years: ");
    		int years = input.nextInt();
    		System.out.print("Enter number of months: ");
    		int months = input.nextInt();
    		input.close();
    		
    		int theDays = 0;
    		boolean falg = (years % 4 == 0 && years % 100 != 0) || years % 400 == 0;
    		if (months == 2) {
        
    			if (falg) {
        
    				theDays = days[0];
    			} else {
        
    				theDays = days[2];
    			}
    		} else {
        
    			theDays = days[months];
    		}
    		System.out.println(month[months] + " " + years  + " has " + theDays + " days");
    	}
    }

### 3.12（回文数字） ###

import java.util.Scanner;
     
    public class Test3_12 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter a three-digit integer: ");
    		int number = input.nextInt();
    		input.close();
    		
    		//判断是否是回文数字
    		int num1 = number % 10;
    		int num2 = number / 100;
    		if(num1 == num2) {
        
    			System.out.println(number + " is a palindrome");
    		}else {
        
    			System.out.println(number + " is not a palindrome");
    		}
    	}
    }

### 3.13（财务应用程序，计算税款） ###

import java.util.Scanner;
     
    public class Test3_13 {
        
    	public static void main(String[] args) {
        
    		Scanner input = new Scanner(System.in);
    		System.out.println("(0-single filer, 1-married jointly or qualifying widow(er),2-married separateiy, 3-head of household)");
    		System.out.print("Enter the filing status: ");
    		int status = input.nextInt();
    		System.out.print("Enter the taxable income: ");
    		double income = input.nextDouble();
    		input.close();
    		
    		double tax = 0;
    		
    		if(status == 0) {
        
    			if(income <= 8350) {
        
    				tax = income * 0.10;
    			}else if(income <= 33950) {
        
    				tax = 8350 * 0.10 + (income - 8350) * 0.15;
    			}else if(income <= 82250) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (income - 33950) * 0.25;
    			}else if(income <= 171550) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (income - 82250) * 0.28;
    			}else if(income <= 372590) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (171550 - 82250) * 0.28
    						+ (income - 171550) * 0.33;
    			}else {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (171550 - 82250) * 0.28
    						+ (372950 - 171550) * 0.33 + (income - 372950) * 0.35;
    			}
    		}else if(status == 1) {
        
    			if(income <= 16700) {
        
    				tax = income * 0.10;
    			}else if(income <= 67900) {
        
    				tax = 16700 * 0.10 + (income - 16700) * 0.15;
    			}else if(income <= 137051) {
        
    				tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (income - 67900) * 0.25;
    			}else if(income <= 208850) {
        
    				tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (income - 137050) * 0.28;
    			}else if(income <= 372590) {
        
    				tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (208850 - 137050) * 0.28
    						+ (income - 208850) * 0.33;
    			}else {
        
    				tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (171550 - 137050) * 0.28
    						+ (372950 - 171550) * 0.33 + (income - 372950) * 0.35;
    			}
    		}else if(status ==2) {
        
    			if(income <= 8350) {
        
    				tax = income * 0.10;
    			}else if(income <= 33950) {
        
    				tax = 8350 * 0.10 + (income - 8350) * 0.15;
    			}else if(income <= 68525) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (income - 33950) * 0.25;
    			}else if(income <= 104425) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (income - 68525) * 0.28;
    			}else if(income <= 372590) {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (104425 - 68525) * 0.28
    						+ (income - 104425) * 0.33;
    			}else {
        
    				tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (104425 - 68525) * 0.28
    						+ (186475 - 104425) * 0.33 + (income - 186475) * 0.35;
    			}
    		}else if(status ==3) {
        
    			if(income <= 11950) {
        
    				tax = income * 0.10;
    			}else if(income <= 45500) {
        
    				tax = 11950 * 0.10 + (income - 11950) * 0.15;
    			}else if(income <= 82250) {
        
    				tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (income - 45500) * 0.25;
    			}else if(income <= 171550) {
        
    				tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (income - 117450) * 0.28;
    			}else if(income <= 372590) {
        
    				tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (171550 - 117450) * 0.28
    						+ (income - 171550) * 0.33;
    			}else {
        
    				tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (171550 - 117450) * 0.28
    						+ (372950 - 171550) * 0.33 + (income - 372950) * 0.35;
    			}
    		}else {
        
    			System.out.println("Error: invalid status");
    			System.exit(1);
    		}
    		System.out.println("Tax is " + (int)(tax * 100) / 100.0);
    	}
    }

### 3.14（游戏，猜硬币正反面） ###

import java.util.Scanner;
     
    public class Test3_14 {
        
    	public static void main(String[] args) {
        
    		int num = (int)(Math.random() * 2);
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter a number: ");
    		int guess = input.nextInt();
    		input.close();
    		
    		if(guess == num) {
        
    			System.out.println("Yes");
    		}else {
        
    			System.out.println("No");
    		}
    	}
    }

以上代码均为个人编写，不当之处，悉请指正。