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交换第一个和最后一个单词,反转所有中间的字符

stringbuilder swap regex arrays java

MARTIN · 技术社区 · 10 月前

说明

古鲁给他的学生布置了一项任务。他给了一个句子,学生们必须交换第一个和最后一个单词,并颠倒所有中间的字符。帮助学生使用java程序解决此任务

要求:

   The words present in the sentence must be more than 2, else print "Invalid Length"

   The word should contain only alphabets and space, else print "<sentence> is an invalid sentence"

注:

   In the Sample Input / Output provided, the highlighted text in bold corresponds to the input given by the user, and the rest of the text represents the output.

   Ensure to follow the object-oriented specifications provided in the question description.

   Ensure to provide the names for classes, attributes, and methods as specified in the question description.

   Adhere to the code template, if provided

请不要使用System.exit(0)终止程序。

示例输入/输出1:

输入句子

你戴口罩了吗

面具ruoy raew uoy Do

示例输入/输出2:

输入句子

读卡器

长度无效

示例输入/输出3:

输入句子

推荐@好友

Reflect@friend是一个无效的句子

代码:-

import java.util.Scanner;

class SentenceProcessor {
    
    // Method to check if the sentence is valid
    public boolean isValidSentence(String sentence) {
        return sentence.matches("[a-zA-Z ]+"); // Only alphabets and spaces allowed
    }

    // Method to process the sentence
    public String processSentence(String sentence) {
        if (!isValidSentence(sentence)) {
            return sentence + " is an invalid sentence";
        }

        String[] words = sentence.trim().split("\\s+"); // Split by whitespace

        if (words.length <= 2) {
            return "Invalid Length";
        }

        // Swap first and last words
        String firstWord = words[0];
        String lastWord = words[words.length - 1];
        words[0] = lastWord;
        words[words.length - 1] = firstWord;

        // Reverse middle words
        for (int i = 1; i < words.length - 1; i++) {
            words[i] = new StringBuilder(words[i]).reverse().toString();
        }

        return String.join(" ", words); // Join words with a space
    }
}

public class UserInterface {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        System.out.println("Enter the sentence");
        String input = sc.nextLine();
        
        SentenceProcessor processor = new SentenceProcessor();
        String result = processor.processSentence(input);
        
        System.out.println(result);
        
        sc.close(); // Close the scanner to avoid resource leaks
    }
}

输出:-

Enter the sentence
Do you wear your mask
mask uoy raew ruoy Do

预期产量:-

Enter the sentence
Do you wear your mask
mask ruoy raew uoy Do

我尝试解决这个问题,但未能获得所需的输出,还尝试使用各种开源,这些开源也无法给我正确的代码,它们反复给我相同的输出(如chatgpt、copilot)

4 回复 | 直到 10 月前

WJS 10 月前

问题是你颠倒了每个单词的字符。但你说你应该颠倒第一个和最后一个单词之间的所有字符。

假设中间的单词是 one two three .
你正在做 eno owt eerht .
你想要的是 eerht owt eno .

请执行以下操作:

获取第一个空格和最后一个空格之间的子字符串。
然后反转中间的子字符串
并按照正确的顺序附加单词和子字符串

// Reverse middle characters (those between first and last word)
int start = sentence.indexOf(" ") + 1;
String middle = new StringBuilder(
        sentence.substring(start, sentence.lastIndexOf(" "))).reverse()
        .toString();

return String.join(" ", lastWord, middle, firstWord); // Join sections with a space

wannaBeDev 10 月前

为了得到想要的结果,你需要交换数组的元素:第二个单词和倒数第二个,第三个单词和最后第三个。。。等等。也许它更容易使用 String.substring 方法用于整个任务,而不是将输入拆分到数组中:

public String processSentence(String sentence) {
    if (!isValidSentence(sentence)) {
        return sentence + " is an invalid sentence";
    }

    int firstSpaceIndex = sentence.indexOf(' ');
    int lastSpaceIndex  = sentence.lastIndexOf(' ');

    String firstWord  = sentence.substring(0, firstSpaceIndex);
    String lastWord   = sentence.substring(lastSpaceIndex + 1);
    String middlePart = sentence.substring(firstSpaceIndex, lastSpaceIndex + 1);

    return lastWord + new StringBuilder(middlePart).reverse() + firstWord;
}

编辑

检查输入字符串是否至少有三个子字符串由空格分隔,即单词计数>2修改您进行验证的第二种方法。这样做可以将处理和验证的任务分开。

public boolean isValidSentence(String sentence) {
    String regex = "^[a-zA-Z]+(\\s[a-zA-Z]+){2,}$";
    return sentence.trim().matches(regex);
}

正则表达式说明: ^[a-zA-Z]+(\\s[a-zA-Z]+){2,}$

^ 确保字符串以第一个子字符串开头。
[a-zA-Z]+ 匹配字母序列(子字符串)。
(\\s[a-zA-Z]+) 匹配一个空格后跟另一个子字符串。
{2,} 确保在第一个子字符串之后至少有2个子字符串。
$ 确保整个字符串都符合图案。

SedJ601 10 月前

您的要求与预期的输出不匹配!

// Method to process the sentence
static public String processSentence(String sentence) {
    if (!isValidSentence(sentence)) {
        return sentence + " is an invalid sentence";
    }

    String[] words = sentence.trim().split("\\s+"); // Split by whitespace

    if (words.length <= 2) {
        return "Invalid Length";
    }

    //Swap all words
    String[] reverseWords = new String[words.length];
    for(int i = words.length - 1; i >= 0; i--)
    {
        reverseWords[(reverseWords.length - 1) - i] = words[i];
    }

    // Reverse middle words
    for (int i = 1; i < words.length - 1; i++) {
        reverseWords[i] = new StringBuilder(reverseWords[i]).reverse().toString();
    }

    return String.join(" ", reverseWords); // Join words with a space
}

输出:

Do you wear your mask
mask ruoy raew uoy Do

Marce Puente 10 月前

错误在这里:

for (int i = 1; i < words.length - 1; i++) {
    words[i] = new StringBuilder( words[i] ).reverse().toString();
}

问题是,你颠倒了中心单词的字母顺序,但没有颠倒它们的顺序,我们可以这样做:

String out = lastWord + " ";
for( int i = words.length - 2; i >= 1; i -- ) {
   out += new StringBuilder( words[ i ] ).reverse().toString() + " ";
}
return out + firstWord;