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文字列が回文かどうかを判断するときに、スペース、句読点、大文字と小文字を考慮しない回文プログラムを作成しようとしています。

先に述べたことを行うために与えられたこのコードを変更するにはどうすればよいですか?

package palindrome;

import java.util.Scanner;

public class Palindrome {

   public static void main (String[] args)
 {
  String str, another = "y";
  int left, right;
  Scanner scan = new Scanner (System.in);

  while (another.equalsIgnoreCase("y")) // allows y or Y
  {
     System.out.println ("Enter a potential palindrome:");
     str = scan.nextLine();



     left = 0;
     right = str.length() - 1;

     while (str.charAt(left) == str.charAt(right) && left < right)
     {
        left++;
        right--;
     }

     System.out.println();

     if (left < right)
        System.out.println ("That string is NOT a palindrome.");
     else
        System.out.println ("That string IS a palindrome.");

     System.out.println();
     System.out.print ("Test another palindrome (y/n)? ");
     another = scan.nextLine();
  }

} }

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2 に答える 2

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The heart of your program is in following loop

while (str.charAt(left) == str.charAt(right) && left < right)
    {
        left++;
        right--;
    }


what you are doing here is to compare the characters without honoring the condition of ignoring space and punctuation here. Your logic should be such that while picking the characters for comparison (either from left or right) you will need to skip that character and move for the next character.
To make picture clearer see the following :

Input string :
inStr = Ma'lyalam

Step 1:
Since you have to ignore the case do following
inStr = inStr.toLowerCase();

Step 2:

 1. int left =0 , right = 8
 2. char chLeft, chRight
 3. chLeft = m , chRight = m 
 4. chLeft == chRight -> true, increment left and decrement right
 5. chLeft = a , chRight = a
 6. chLeft == chRight -> true, increment left and decrement right
 7. chLeft = ' , chRight = l -> Since chLeft = ' skip it, increment left so chLeft = l. Now continue like above

so the code should look like

    boolean isPlaindrome = false;
    str = str.toLowerCase();
    char chLeft, chRight;
    while (left < right)
    {
    chLeft = str.charAt(left);
    chRight = str.charAt(right)
    if (chLeft == ''' || chLeft == ' ')
     {
       left++
       continue;
     }
     else if (chRight == ''' || chRight == ' ')
     {
       right--;
       continue;
     }

     if (chLeft == chRight)
    {
     left++; right--;
    }
    else
    {
    break;
    }
    }

    if (left == right)
     isPlaindrome = true;
于 2011-10-12T03:17:31.333 に答える