Question

Debug following methods(longestRun(finds how many times a character got repeated), findLastP(finds last p in a string), findFirstP(finds first p in a string)) in java language. 

public class simpleLoops
{

/**
* @param args
*/
public static void main(String[] args)
{
   System.out.println(longestRun("aabbbccd"));
   System.out.println("Expected 3");
   System.out.println(longestRun("aaa"));
   System.out.println("Expected 3");
   System.out.println(longestRun("aabbbb"));
   System.out.println("Expected 4");
  
  
   int count = countP("Mississippi");
System.out.println(count);
  
int result = findLastP("Mississippi");
System.out.println(result);

result = findFirstP("stop");
System.out.println(result);

result = findFirstP("xxxyyyzzz");
System.out.println(result);
}

/**
* Returns the number of P's in a string.
* @param s
* the string to examine
* @return
* number of P's in s
*/
private static int countP(String s)
{
int count = 0;
int i = 0;
while (i < s.length())
{

if (isLetterP(s.charAt(i)))
{
count += 1;
}
i += 1;
}
return count;
}
  
/**
* Returns the index of the last P in a string, or -1 if the
* string contains no P's.
* @param s
* the string to examine
* @return
* index of the last P, or -1
*/
private static int findLastP(String s)
{
int i = 0;
while (i < s.length())
{
// start at the end of the string
int index = s.length() - i - 1;
if (isLetterP(s.charAt(index)))
{
return index;
}
index = index - 1;
}
  
// didn't find a P
return -1;
}
  
/**
* Returns the index of the first P in a string, or -1 if the
* string contains no P's.
* @param s
* the string to examine
* @return
* index of the first vowel, or -1
*/
private static int findFirstP(String s)
{
int i = 0;
while (i <= s.length())
{
if (isLetterP(s.charAt(i)))
{
return i;
}
i = i + 1;
}
  
// didn't find a P
return -1;
}
public static int longestRun(String s)
{
int count = 1;
int max = 1;
  
// start with the first character, see how long a run there is
char current = s.charAt(0);
for (int i = 1; i < s.length() - 1; i += 1)
{
char c = s.charAt(i);
if (c == current)
{
// matches the 'current' character, add 1
count += 1;
}
else
{
// that was the end of the run; if it was a longer run, make that the max
if (count > max)
{
count = max;
}

// start counting a new run of a different character
current = c;   
}
}
  
// this should be the length of the longest run we found
return max;
}
  
/**
* Returns true if the given character is the letter "P" (lowercase
* or uppercase), false otherwise
* the character to check
* @return
* true if the given character is a "P", false otherwise
*/
private static boolean isLetterP(char ch)
{
return ch == 'p' || ch == 'P';
}
}

Answer 1

ANSWER:-

CODE:-

public class SimpleLoops
{

   /**
   * @param args
   */
   public static void main(String[] args)
   {
        System.out.println(longestRun("aabbbccd"));
        System.out.println("Expected 3");
        System.out.println(longestRun("aaa"));
        System.out.println("Expected 3");
        System.out.println(longestRun("aabbbb"));
        System.out.println("Expected 4");
  
  
        int count = countP("Mississippi");
       System.out.println(count);
      
       int result = findLastP("Mississippi");
       System.out.println(result);

       result = findFirstP("stop");
       System.out.println(result);

       result = findFirstP("xxxyyyzzz");
       System.out.println(result);
   }

   /**
   * Returns the number of P's in a string.
   * @param s
   * the string to examine
   * @return
   * number of P's in s
   */
   private static int countP(String s)
   {
       int count = 0;
       int i = 0;
       while (i < s.length())
       {

           if (isLetterP(s.charAt(i)))
           {
               count += 1;
           }
           i += 1;
       }
       return count;
   }
  
   /**
   * Returns the index of the last P in a string, or -1 if the
   * string contains no P's.
   * @param s
   * the string to examine
   * @return
   * index of the last P, or -1
   */
   private static int findLastP(String s)
   {
       int index = s.length() - 1;
       while (index >= 0)
       {
           // start at the end of the string
          
           if (isLetterP(s.charAt(index)))
           {
               return index;
           }
           index = index - 1;
       }
      
       // didn't find a P
       return -1;
   }
  
   /**
   * Returns the index of the first P in a string, or -1 if the
   * string contains no P's.
   * @param s
   * the string to examine
   * @return
   * index of the first vowel, or -1
   */
   private static int findFirstP(String s)
   {
       int i = 0;
       while (i < s.length())
       {
           if (isLetterP(s.charAt(i)))
           {
           return i;
           }
           i = i + 1;
       }
  
       // didn't find a P
       return -1;
   }
   public static int longestRun(String s)
   {
       int count = 1;
       int max = 1;
      
       // start with the first character, see how long a run there is
       char current = s.charAt(0);
       for (int i = 1; i < s.length(); i++)
       {
           char c = s.charAt(i);
           if (c == current)
           {
               // matches the 'current' character, add 1
               count += 1;
           }
           else
           {
               // that was the end of the run; if it was a longer run, make that the max
               if (count > max)
               {
                   max = count;
               }
               count = 1;
               // start counting a new run of a different character
               current = c;
           }
       }
       if(count > max)
           max = count;
       // this should be the length of the longest run we found
       return max;
   }
  
   /**
   * Returns true if the given character is the letter "P" (lowercase
   * or uppercase), false otherwise
   * the character to check
   * @return
   * true if the given character is a "P", false otherwise
   */
   private static boolean isLetterP(char ch)
   {
       return ch == 'p' || ch == 'P';
   }
}

CHANGES:-

IN longestRun method,

   1.max = count; -> you need to assign count to max. But you assigned max to count;

   2. count = 1; -> you need to reset count to 1 when old run ends.

findLastP method:-

1. int index = s.length()-1;

   you just need to start from end of the string. no need of i variable.

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             THANK YOU!!!!

OUTPUT:-