Java程序设计基础练习50题(中)

痛定思痛。 2022-10-17 04:27 161阅读 0赞

### 文章目录 ###

*  3 程序调试
 *   *  E201\_03 \_01评委评分
     *  E201\_03 \_02判断水仙花数
 *  4 循环
 *   *  E201\_04\_01存钱翻倍
     *  E201\_04\_02统计法计算圆周率
     *  E201\_04\_03\_计算数列之和
     *  E201\_04\_04\_输出所有水仙花数
     *  E201\_04\_05验证角谷定理
     *  E201\_04\_06 输出100以内的素数
     *  E201\_04\_07九九乘法表
     *  E201\_04\_08\_输出1000以内的完数
 *  5 数组
 *   *  E201\_05\_01\_成绩统计
     *  E201\_05\_02\_数组交集
     *  E201\_05\_03\_数组并集
     *  E201\_05\_04\_超大数相加
     *  E201\_05\_06\_矩阵转置
     *  E201\_05\_07\_杨辉三角

--------------------

[Java程序设计基础练习50题(上)][Java_50]  
[Java程序设计基础练习50题(下)][Java_50 1]

# 3 程序调试 #

## E201\_03 \_01评委评分 ##

面的程序存在错误，请调试并排除错误

> public static void main(String\[\] args) \{  
> System.out.println(“请依次输入5个评委的评分在（0-100）：”);  
> Scanner scan = new Scanner(System.in);  
> int score1 = scan.nextInt();  
> int score2 = scan.nextInt();  
> int score3 = scan.nextInt();  
> int score4 = scan.nextInt();  
> int score5 = scan.nextInt();  
> int min = 100;  
> if(score1 < min)\{  
> min = score1;  
> \}  
> if(score2 < min)\{  
> min = score1;  
> \}  
> if(score3 < min)\{  
> min = score1;  
> \}  
> if(score4 < min)\{  
> min = score1;  
> \}  
> if(score5 < min)\{  
> min = score1;  
> \}  
> int max = 0;  
> if(score1 > max)\{  
> max = score1;  
> \}  
> if(score2 > max)\{  
> max = score1;  
> \}  
> if(score3 > max)\{  
> max = score1;  
> \}  
> if(score4 > max)\{  
> max = score1;  
> \}  
> if(score5 > max)\{  
> max = score1;  
> \}  
> int total = score1+score2+score3+score4+score5;  
> float ave = (total-max-min)/5;  
> System.out.println("");  
> \}

package e201_03_01;
    import java.util.Scanner;
    
    public class MamberGrade {
        
    	public static void main(String[] args) {
        
    	    System.out.println("请依次输入5个评委的评分在（0-100）：");
    	    Scanner scan = new Scanner(System.in);
    	    int score1 = scan.nextInt();
    	    int score2 = scan.nextInt();
    	    int score3 = scan.nextInt();
    	    int score4 = scan.nextInt();
    	    int score5 = scan.nextInt();
    
    	    int min = 100;
    	    if(score1 < min){
        
    	        min = score1;
    	    }
    	    if(score2 < min){
        
    	        min = score2;
    	    }
    	    if(score3 < min){
        
    	        min = score3;
    	    }
    	    if(score4 < min){
        
    	        min = score4;
    	    }
    	    if(score5 < min){
        
    	        min = score5;
    	    }
    	    int max = 0;
    	    if(score1 > max){
        
    	        max = score1;
    	    }
    	    if(score2 > max){
        
    	        max = score2;
    	    }
    	    if(score3 > max){
        
    	        max = score3;
    	    }
    	    if(score4 > max){
        
    	        max = score4;
    	    }
    	    if(score5 > max){
        
    	        max = score5;
    	    }
    	    int total = score1+score2+score3+score4+score5;
    	    float ave = (float) ((total-max-min)/3.0);
    
    	    //System.out.println("");
    	    System.out.println(ave);
    	}
    }

## E201\_03 \_02判断水仙花数 ##

题目要求：下面的程序存在错误，请调试并排除错误

> public static void main(String\[\] args) \{  
> System.out.println(“请输入一个三位数：”);  
> Scanner scan = new Scanner(System.in);  
> int num = scan.nextInt();  
> if(num<100 && num>999)\{  
> System.out.println(num+“不是一个三位数”);  
> return;  
> \}  
> int b100 = num/100;  
> int b10 = num%100/10;  
> int b1 = num%10;  
> boolean result = b100*b100*b100+b10*b10*b10+b1*b1*b1 == num;  
> if(result = true)\{  
> System.out.println(num+“是水仙花数”);  
> \}else\{  
> System.out.println(num+“不是水仙花数”);  
> \}  
> \}

package e201_03_02;
    
    import java.util.Scanner;
    
    public class shuixianhau {
        
    
    	public static void main(String[] args) {
        
    	    System.out.println("请输入一个三位数：");
    	    Scanner scan = new Scanner(System.in);
    	    int num = scan.nextInt();
    
    	    if(num<100 && num>999){
        
    	        System.out.println(num+"不是一个三位数");
    	        return;
    	    }
    
    	    int b100 = num/100;
    	    int b10 = num/10%10;
    	    int b1 = num%10;
    
    	    boolean result = b100*b100*b100+b10*b10*b10+b1*b1*b1 == num;
    	    if(result == true){
        
    	        System.out.println(num+"是水仙花数");
    	    }else{
        
    	        System.out.println(num+"不是水仙花数");
    	    }
    	}
    
    }

# 4 循环 #

## E201\_04\_01存钱翻倍 ##

假定银行一年期存款利率为3%，到期后自动转存，问一万元需要连续存多少年才能超过2万元

package e201_04_01;
    
    public class moneydouble {
        
    
    	public static void main(String[] args) {
        
    		double money=10000;
    		int n = 0;
    		while(money<20000) {
        
    			money=money*1.03;
    			n=n+1;
    		}
    		System.out.println("Need to keep it for "+n+" years");
    	}
    
    }

## E201\_04\_02统计法计算圆周率 ##

随机数法求解π，向正方形中扔点，如果落在圆内在计数，重复这个过程，然后用该计数除以总次数就是π的四分之一。

package e201_04_02;
    
    public class MoncatelloPI {
        
    	public static void main(String[] args) {
        
    		int n=100000;
    		double x=0.0;
    		double y=0.0;
    		double pi1=0.0;
    		double in=0;
    		for (int i=0;i<n;i++) {
        
    			x=Math.random();
    			y=Math.random();
    			if(Math.sqrt(x*x+y*y)<1.0) {
        
    				in++;
    			}
    		}
    		pi1=4*in/n;
    		System.out.println("The pi is "+pi1);
    	}
    }

## E201\_04\_03\_计算数列之和 ##

编程计算数列的前20项之和：1/2,2/3,3/5,5/8……

package e201_04_03;
    
    public class seriesSummation {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		double n = 0;
    		double x = 1.0;
    		double y = 2.0;
    		double sum = 0;
    		while(n<20.0) {
        
    			sum=sum+x/y;
    			double t = y;
    			y = x+y;
    			x = t;
    			n=n+1;
    		}
    		System.out.println("The sum of the series is "+sum);
    
    	}
    
    }

## E201\_04\_04\_输出所有水仙花数 ##

package e201_04_04;
    
    public class narcissusNumber {
        
    	public static void main(String[] args) {
        
    		for (int i = 100; i <1000 ; i++) {
        
    			int firstNum = i/100;
    			int secondNum = i/10%10;
    			int thirdNum = i%10;
    			if(Math.pow(firstNum, 3) + Math.pow(secondNum, 3)+Math.pow(thirdNum, 3) == i){
        
    				System.out.println("The narcissus number is：" + i);
    			}
    		}
    	}
    }

## E201\_04\_05验证角谷定理 ##

任意一个自然数，若为偶数则除以2，若为奇数则乘以3加1，得到新的自然数，经过若干次这样演算，最终结果必然为1。要求显示验证的步骤。

package e201_04_05;
    
    import java.util.Scanner;
    
    public class ValleyAngleTheorem {
        
    	static int i = 0;
    	@SuppressWarnings("resource")
    	public static void main(String[] args) {
        
    		System.out.println("please input a number:");
    		Scanner sca = new Scanner(System.in);
    		int n = sca.nextInt();
    		int i = count(n);
    		System.out.println("step=" +i);
    	}
    
    	public static int count(int n) {
        
    		if (n == 1) {
        
    			System.out.println(n);
    			i++;
    		}else if (n % 2 == 0) {
        
    			System.out.println(n);
    			count(n / 2);
    			i++;
    		}else {
        
    			System.out.println(n);
    			count(n * 3 + 1);
    			i++;
    		}
    		return i;
    	}
    
    }

## E201\_04\_06 输出100以内的素数 ##

package e201_04_06;
    
    public class PrimeNumber {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		int n=100;
    		int i=0;
    		for(i=2;i<n;i++) {
        
    			boolean flag=true;
    			for (int j = 2; j < i/2+1; j++) {
        
    				if (i%j==0) {
        
    					flag=false;
    				}
    			}
    			if (flag==true) {
        
    				System.out.println(i+" is prime");
    			}
    		}
    	}
    }

## E201\_04\_07九九乘法表 ##

package e201_04_07;
    
    public class multiplicationTable {
        
    	public static void main(String[] args){
        
    		for(int i=1;i<=9;i++){
        
    			for(int j=1;j<=i;j++){
        
    				System.out.print(j+"*"+i+"="+(i*j)+"  ");
    			}
    			System.out.println();
    		}
    	}
    }

## E201\_04\_08\_输出1000以内的完数 ##

package e201_04_08;
    
    public class perfectNumber {
        
    	public static void main(String[] args) {
        
    		
    		for(int i=2;i<1000;i++) {
        
    			int sum=0;
    			for(int j=1;j<i;j++) {
        
    				if(i%j==0) {
        
    					sum+=j;
    				}
    			}
    			if(sum==i) {
        
    				System.out.print(sum + " ");
    			}
    		}
    		
    	}
    }

# 5 数组 #

## E201\_05\_01\_成绩统计 ##

根据学生的考试成绩，计算最高分、最低分、平均分和标准差。

package e201_05_01;
    
    import java.util.Arrays;
    import java.util.Scanner;
    
    public class grade {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		@SuppressWarnings("resource")
    		Scanner sca = new Scanner(System.in);
    		System.out.println("please input numbers of student:");
    		int n= sca.nextInt();double[] score = new double[n];
    		double sum=0;double total=0;
    		for (int i=0;i<score.length;i++) {
        
    			System.out.print("please input grade of sutdent");
    			score[i]=sca.nextDouble();sum+=score[i];
    		}
    		Arrays.sort(score);
    		double avg=sum/n;double max=score[n-1];double min=score[0];
    		for(int i=0;i<score.length;i++){
        
    		    total += (score[i]-avg)*(score[i]-avg);
    		}
    		double sta = Math.sqrt(total/score.length);
    		System.out.println("Top score is "+max+" ,lowest mark is "+min+" ,average score is "+avg+" , standard deviation is "+sta);
    	}
    
    }

## E201\_05\_02\_数组交集 ##

package e201_05_02;
    
    import java.util.ArrayList;
    
    public class arrayOverlap {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		String[] arr1 = {
         "1", "2", "3" };
    		String[] arr2 = {
         "4", "5", "3" };
            System.out.println("The intersection of the array is："+retain(arr1,arr2)); 
            
    	}
    
    	private static ArrayList<Object> retain(String[] a, String[] b){
        
    		ArrayList<Object> a1 = new ArrayList<>();
            ArrayList<Object> b1 = new ArrayList<>();
    		for(String str : a) {
        
    			a1.add(str);
    		}
    		for(String str : b) {
        
    			b1.add(str);
    		}
    		b1.retainAll(a1);//求交集
    		return b1;	
    	}
    }

## E201\_05\_03\_数组并集 ##

package e201_05_03;
    import java.util.HashSet;
    import java.util.Set;
     
    public class arrayUnion {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		String[] arr1 = {
         "1", "2", "3" };
            String[] arr2 = {
         "4", "5", "6" };
            System.out.println("The union of arrays is："+union(arr1, arr2));
    	}
    	private static Set<Object> union(String[] arr1, String[] arr2) {
        
    		Set<Object> m=new HashSet<>();
    		for (String str : arr1) {
        
                m.add(str);
            }
            for (String str : arr2) {
        
                m.add(str);
            }
            return m;
        }
    
    }

## E201\_05\_04\_超大数相加 ##

长整型数据为32位，能表示的最大值为232-1，但是在很多情况下是不够用的，需要程序设计者自行解决这个问题。例如可以通过数组存储超长整数的每一位数值，对应位相加，如果超过9则产生进位。这里假设运算数据和结果都不超过30位。

package e201_05_04;
    
    import java.math.BigDecimal;
    import java.util.Scanner;
    
    public class largeNumber {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		@SuppressWarnings("resource")
    		Scanner sca = new Scanner(System.in);
            String s1 = sca.nextLine();
            String s2 = sca.nextLine();
            BigDecimal b1 = new BigDecimal(s1);
            BigDecimal b2 = new BigDecimal(s2);
            System.out.println("The sum of the large numbers is:"+b1.add(b2));
        }
    
    }

## E201\_05\_06\_矩阵转置 ##

输出用户输入的矩阵，输出其对应的转置矩阵。

package e201_05_06;
    
    import java.util.Arrays;
    import java.util.Scanner;
    
    public class matrixTranspose {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
    		@SuppressWarnings("resource")
    		Scanner sca = new Scanner(System.in);
    		System.out.println("The rank of the matrix is:");
    		int n = sca.nextInt();
    		int a[][] = new int[n][n];
    		System.out.println("Please input a matrix:");
    		for (int i = 0; i < n; i++) {
        
    			for (int j = 0; j < n; j++) {
        
    				a[i][j] = sca.nextInt();
    			}
    		}
    		int b[][] = new int[n][n];
    		for (int i = 0; i < n; i++) {
        
    			for (int j = 0; j < n; j++) {
        
    				b[i][j] = a[j][i];
    			}
    		}
    		System.out.println("This matrix is:");
    		for(int i=0; i<a.length; i++){
        
    			System.out.println(Arrays.toString(a[i]));
    		}
    		System.out.println("Inverse matrix is:");
    		for(int i=0; i<b.length; i++){
        
    			System.out.println(Arrays.toString(b[i]));
    		}
    	}
    
    }

## E201\_05\_07\_杨辉三角 ##

package e201_05_07;
    
    import java.util.Arrays;
    import java.util.Scanner;
    public class yanghui {
        
    	public static void main(String[] args) {
        
    		@SuppressWarnings("resource")
    		Scanner sca = new Scanner(System.in);
    		System.out.println("please input line number:");
    		int n = sca.nextInt();
    		int[][] arr = new int[n][];
    		arr[0]=new int[1];
    		arr[0][0]=1;
    		for( int i=0;i<arr.length;i++) {
        
    			arr[i]=new int[i+1];arr[i][0]=arr[i][i]=1;
    			for( int j=1;j<i;j++) {
        
    				arr[i][j]=arr[i-1][j-1]+arr[i-1][j];
    			}
    		}
    		for(int i=0;i<arr.length;i++) {
        
    			System.out.println(Arrays.toString(arr[i]));
    		}
    		
    	}
    
    }

[Java_50]: https://blog.csdn.net/weixin_44037272/article/details/117450680
[Java_50 1]: https://blog.csdn.net/weixin_44037272/article/details/117450801