目录

题目一text1464

题目二text7183

题目三text7184

题目四text7185

题目五text7186

题目六text7193

题目七text7194

 题目八text7195

题目九text7197

 题目十text7196

题目一text1464

import java.util.Scanner;
public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);int [][]a = new int[4][4];for(int i = 0;i < 4;i++)for(int j = 0;j < 4;j++){a[i][j] = input.nextInt();}int maxn = a[0][0];int maxi = 0, maxj = 0;for(int i = 0; i < 4; i ++) {for(int j = 0; j < 4; j ++) {if(maxn < a[i][j]) {maxn = a[i][j];maxi = i;maxj = j;}}}System.out.println("max="+maxn);System.out.println("x=" + maxi + " y=" + maxj);}
}

题目二text7183

import java.util.Scanner;
import java.util.stream.IntStream;public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);int[] arr = {input.nextInt(), input.nextInt(), input.nextInt()};IntStream.of(arr).sorted().forEach(num -> System.out.print(num + " "));}
}

这里，我们将整数数组转换为一个IntStream对象，然后使用sorted()方法将它们进行排序。最后，我们使用forEach()方法遍历排序后的流中的每个元素，并将它们打印到标准输出中。

题目三text7184

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);// 读取用户输入的形状System.out.print("请输入形状（圆形或矩形）：");String shape = input.next();if (shape.equals("圆形")) {// 如果是圆形，读取半径，并计算面积System.out.print("请输入半径：");double radius = input.nextDouble();double area = Math.PI * radius * radius;System.out.println("圆形的面积为：" + area);} else if (shape.equals("矩形")) {// 如果是矩形，读取长和宽，并计算面积System.out.print("请输入长：");double length = input.nextDouble();System.out.print("请输入宽：");double width = input.nextDouble();double area = length * width;System.out.println("矩形的面积为：" + area);} else {// 如果不是圆形也不是矩形，输出错误信息System.out.println("输入错误，只能输入圆形或矩形。");}}
}

 优化

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);// 读取用户输入的形状System.out.print("请输入形状（圆形或矩形）：");String shape = input.next();try {switch (shape) {case "圆形":// 如果是圆形，读取半径，并计算面积System.out.print("请输入半径：");double radius = input.nextDouble();double area = Math.PI * radius * radius;System.out.println("圆形的面积为：" + area);break;case "矩形":// 如果是矩形，读取长和宽，并计算面积System.out.print("请输入长：");double length = input.nextDouble();System.out.print("请输入宽：");double width = input.nextDouble();area = length * width;System.out.println("矩形的面积为：" + area);break;default:// 如果不是圆形也不是矩形，输出错误信息throw new IllegalArgumentException("输入错误，只能输入圆形或矩形。");}} catch (Exception e) {// 捕获异常并输出错误信息System.out.println(e.getMessage());}}
}

题目四text7185

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);// 读取用户输入的形状System.out.print("输入一个大于1正整数n：");int n = input.nextInt();if(n <= 1)System.out.println("输入n不是大于1正整数");else {for (int i = 1; i <= n; i++) {if (isPrime(i))System.out.print(i + " ");}}}public static boolean isPrime(int n){if(n <= 1)return false;if(n == 2){return true;}for(int i = 2;i <= Math.sqrt(n);i++)if(n % i == 0)return false;return true;}
}

优化

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.print("输入一个大于1正整数n：");int n;try {n = scanner.nextInt();if (n <= 1) {throw new Exception("输入n不是大于1正整数");}System.out.print("n以内的素数为：");for (int i = 2; i <= n; i++) {if (isPrime(i)) {System.out.print(i + " ");}}} catch (Exception e) {System.out.println("错误：" + e.getMessage());}}public static boolean isPrime(int n) {if (n < 2) {return false;}for (int i = 2; i <= Math.sqrt(n); i++) {if (n % i == 0) {return false;}}return true;}
}

题目五text7186

import java.util.Scanner;public class Main{public static void main(String[] args) {int[] array = {-2, 1, 4, 5, 8, 12, 17, 23, 45, 56, 90, 100};Scanner in = new Scanner(System.in);System.out.print("输入一个整数n：");int n = in.nextInt();int flag = 1;for(int i = 0; i < 12; i ++) {if(n == array[i]) {System.out.println(n + "是数组中的第" + i + "个元素");flag = 0;break;}}if(flag == 1) {System.out.println(n + "不在数组中");}}
}

 优化

import java.util.Arrays;
import java.util.Scanner;public class Main {private static final int[] ARRAY = {-2, 1, 4, 5, 8, 12, 17, 23, 45, 56, 90, 100};private static final int ARRAY_LENGTH = ARRAY.length;public static void main(String[] args) {Scanner in = new Scanner(System.in);System.out.print("输入一个整数n：");int n = in.nextInt();int index = Arrays.binarySearch(ARRAY, n);if (index >= 0) {System.out.println(n + "是数组中的第" + (index + 1) + "个元素");} else {System.out.println(n + "不在数组中");}}
}

题目六text7193

​
import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);double f = input.nextDouble();double c = 5 * (f - 50) / 9 + 10;System.out.printf("The temperature is %.2f.", c);}
}​

优化

import java.util.InputMismatchException;
import java.util.Scanner;
public class Main {public static void main(String[] args) {Scanner input = new Scanner(System.in);double f = 0;try {f = input.nextDouble();} catch (InputMismatchException e) {System.out.println("Invalid input. Please enter a number.");return;}double c = 5 * (f - 50) / 9 + 10;System.out.printf("The temprature is​ %.2f.",c);}
}

题目七text7194

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int repeat = sc.nextInt();for (int i = 0; i < repeat; i++) {int a = sc.nextInt();int n = sc.nextInt();long sum = 0;long base = 1; for (int j = 1; j <= n; j++) {sum += base * a;base = base * 10 + 1;}System.out.println(sum);}}
}
​

 题目八text7195

import java.util.Arrays;
import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner in = new Scanner(System.in);System.out.print("输入一个四位整数n：");int n = in.nextInt();int digit1 = n % 100;int digit2 = n / 10 % 10;int digit3 = n / 100 % 10;int digit4 = n / 1000;digit1 = (digit1 + 9) % 10;digit2 = (digit2 + 9) % 10;digit3 = (digit3 + 9) % 10;digit4 = (digit4 + 9) % 10;int number =  digit2 * 1000 + digit1 * 100 + digit4 * 10 + digit3;System.out.println("The encrypted number is " + number);}
}

优化

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner in = new Scanner(System.in);System.out.print("输入一个四位整数n：");int n = in.nextInt();int[] digits = new int[4];digits[0] = n % 10;digits[1] = n / 10 % 10;digits[2] = n / 100 % 10;digits[3] = n / 1000;for (int i = 0; i < 4; i++) {digits[i] = (digits[i] + 9) % 10;}int encryptedNumber = digits[2] * 1000 + digits[1] * 100 + digits[0] * 10 + digits[3];System.out.printf("加密后的数字为：%04d", encryptedNumber);}
}

题目九text7197

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int repeat = sc.nextInt();for (int i = 0; i < repeat; i++) {int a = sc.nextInt();int n = sc.nextInt();long sum = 0;long base = 1; for (int j = 1; j <= n; j++) {sum += base * a;base = base * 10 + 1;}System.out.println(sum);}}
}
​

 题目十text7196

import java.util.Scanner;public class Main {public static void main(String[] args) {int n;Scanner scanner = new Scanner(System.in);n = scanner.nextInt();//write your codeint flag = -1;double num = 0.0f;double numerator; // 分子double denominator; //分母for(int i = 1; i <= n; i ++) {flag = flag * (-1);numerator = flag;denominator = (i-1) * 3 + 1;num = num + (numerator / denominator);}System.out.println(num);}
}