java—如何编写代码来指示用户输入的文本中的第一个位置违反了回文属性?

c90pui9n  于 2021-07-03  发布在  Java
关注(0)|答案(1)|浏览(374)

假设我输入“在你看到厄尔巴之前你有能力”。这看起来像回文,直到您看到“were”中的第一个“e”,因此此文本的输出将是:这不是在:ablewe检测到的回文不匹配
下面是司机

public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String line;

        do {

            // prompt user for input String and store it in line
            System.out.print("Enter an expression (or hit Enter to exit) : ");
            line = input.nextLine();

            // convert input String to upper case
            line = line.toUpperCase();

            // if user hits Enter or simply types in spaces and hits enter, break out of loop
            if (line.trim().isEmpty()) {
                break;
            }

            // call isPalindrom
            // if it returns true, display one message, else display another
            if (Palindrome.isPalindrome(line)) {
                System.out.println("Your expression is a palindrome.");
            } else {
                System.out.println("Your expression is not a palindrome.");
            }

        } while (line.length() != 0);

        System.out.println("You didn't enter an expression.  Exiting application ...");
    }
}

下面是具有isAlindrome方法的类

public static boolean isPalindrome(String input){

        // create Queue and Stack of Characters
        // to store the input String
        Queue<Character> q = new LinkedList<>();
        Stack<Character> s = new Stack();

        // temporarily store the individual Characters
        // in input String before they're pushed onto
        // Stack and added to Queue
        Character letter;

        // keep track of differences between Characters
        // in Stack and Queue
        int mismatches = 0;

        // loop through input String
        for (int i = 0; i < input.length(); i++){
            // get current Character
            letter = input.charAt(i);

            // if the current Character is an alphabetic character
            if (Character.isLetter(letter)){
                // push it onto the Stack
                s.push(letter);
                // add it to the Queue
                q.add(letter);
            }
        }

        // while the Queue isn't empty
        while (!q.isEmpty()){
            // remove a Character from the Queue
            // pop a Character from the Stack
            // if they're not equal, increment mismatches
            if (!q.remove().equals(s.pop()))
                // Stack will produce the input String backwards
                // Queue will produce the input String forwards
                mismatches++;
        }

        // return true if there are no mismatches, else return false
        return (mismatches == 0);
    }
}

我需要输出来显示不匹配发生的位置

snz8szmq

snz8szmq1#

创建字符串( allLetters 在下面给出的代码中)用空字符串替换所有非字母,即。 input.replaceAll("[^\\p{L}]", "") 哪里 ^\\p{L} 指定非字母字符。
使用变量( index 在下面给出的代码中)跟踪已处理的字母的位置。当检测到不匹配时,打印 allLetters.substring(0, index + 1) 打破循环。
代码:

int index = 0;
String allLetters = input.replaceAll("[^\\p{L}]", "");
// while the Queue isn't empty
while (!q.isEmpty()) {
    // remove a Character from the Queue
    // pop a Character from the Stack
    // if they're not equal, increment mismatches
    if (!q.remove().equals(s.pop())) {
        // Stack will produce the input String backwards
        // Queue will produce the input String forwards
        mismatches++;
        System.out.println("Mismatch detected at: " + allLetters.substring(0, index + 1));
        break;
    }
    index++;
}

示例运行:

Enter an expression (or hit Enter to exit) : Able were you ere you saw Elba
Mismatch detected at: ABLEWE
Your expression is not a palindrome.
Enter an expression (or hit Enter to exit) :

注意:当前,您正在将转换为大写的用户输入传递给函数, isPalindrome 因此输出字符串( ABLEWE 在上面显示的示例运行中)是大写的。换个案子的好地方应该在里面 isPalindrome 如下所示:

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;
import java.util.Stack;

public class Palindrome {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String line;

        do {

            // prompt user for input String and store it in line
            System.out.print("Enter an expression (or hit Enter to exit) : ");
            line = input.nextLine();

            // if user hits Enter or simply types in spaces and hits enter, break out of
            // loop
            if (line.trim().isEmpty()) {
                break;
            }

            // call isPalindrom
            // if it returns true, display one message, else display another
            if (Palindrome.isPalindrome(line)) {
                System.out.println("Your expression is a palindrome.");
            } else {
                System.out.println("Your expression is not a palindrome.");
            }

        } while (line.length() != 0);

        System.out.println("You didn't enter an expression.  Exiting application ...");
    }

    public static boolean isPalindrome(String input) {
        // Create a string by replacing all non-letters by empty string
        String allLetters = input.replaceAll("[^\\p{L}]", "");

        // convert input String to upper case
        input = input.toUpperCase();

        // create Queue and Stack of Characters
        // to store the input String
        Queue<Character> q = new LinkedList<>();
        Stack<Character> s = new Stack();

        // temporarily store the individual Characters
        // in input String before they're pushed onto
        // Stack and added to Queue
        Character letter;

        // keep track of differences between Characters
        // in Stack and Queue
        int mismatches = 0;

        // loop through input String
        for (int i = 0; i < input.length(); i++) {
            // get current Character
            letter = input.charAt(i);

            // if the current Character is an alphabetic character
            if (Character.isLetter(letter)) {
                // push it onto the Stack
                s.push(letter);
                // add it to the Queue
                q.add(letter);
            }
        }

        int index = 0;
        // while the Queue isn't empty
        while (!q.isEmpty()) {
            // remove a Character from the Queue
            // pop a Character from the Stack
            // if they're not equal, increment mismatches
            if (!q.remove().equals(s.pop())) {
                // Stack will produce the input String backwards
                // Queue will produce the input String forwards
                mismatches++;
                System.out.println("Mismatch detected at: " + allLetters.substring(0, index + 1));
                break;
            }
            index++;
        }

        // return true if there are no mismatches, else return false
        return (mismatches == 0);
    }
}

示例运行:

Enter an expression (or hit Enter to exit) : Able were you ere you saw Elba
Mismatch detected at: Ablewe
Your expression is not a palindrome.
Enter an expression (or hit Enter to exit) :

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