/**
 * Assignment #5
 * Program to find repeated characters.
 * Author: Mark Allen Weiss
 * SSN: 000-00-0000
 * Course: COP-2210 Section 8
 * Date: October 26, 1998
 *
 * CERTIFICATION OF SOLE AUTHORSHIP
 * I certify that this work is solely my own and
 * that none if it is the work of any other person.
 * I further certify that I have not provided any
 * assistance to other students enrolled in COP-2210 that
 * would render their CERTIFICATION OF SOLE AUTHORSHIP
 * invalid. I understand that violations of this pledge
 * may result in severe sanctions.
 *
 *
 *
 * -----------------------------------
 *   (Mark Allen Weiss)       <--- Put your name here, and sign above
 */

#include <iostream.h>
#include "apstring.h"

const int EMPTY_STRING_POS = -1;

int IndexOfDuplicates( apstring str );
void Process( apstring str );

int main( )
{
    apstring str;

    Process( "aardvark" );
    Process( "access" );
    Process( "" );
    Process( "3432433312" );

    cout << "Enter a string: ";
    cin >> str;
    Process( str );

    return 0;
}


/**
 * Find the most consuctive identical characters.
 * Return the index where these characters start.
 */
int IndexOfDuplicates( apstring str )
{
    int maxDuplicates = 0;
    int currentDuplicates = 0;
    int index = 0;
    int i = 0;
    int j;

    if( str == "" )
        return EMPTY_STRING_POS;

    for( i = 0; i < str.length( ); i = j )
    {
        for( j = i + 1; j < str.length( ) && str[ j ] == str[ i ]; j++ )
            ;
          // At the end of the loop, j is at the first non-matching character
        currentDuplicates = j - i;
        if( currentDuplicates > maxDuplicates )
        {
            maxDuplicates = currentDuplicates;
            index = i;
        }
     }
 
     return index;
}

/**
 * Print out the return value from IndexOfDuplicates and
 * the position that is repeated.
 */
void Process( apstring str )
{
    int pos = IndexOfDuplicates( str );

    if( pos == EMPTY_STRING_POS )
        cout << "Empty string; return value is " << pos << endl;
    else
    {
        cout << "For " << str << " the maximal duplicate sequence starts at "
             << pos << ", which is a '" << str[ pos ] << "'" << endl;
    }
}