// grades.cxx
/**********************************************
/* This program will calculate and print the 
/* average grade of all the students in a class.
/* In addition, it will display the distribution of 
/* grades in the class, as well as the class maximum and
/* class minimum. The user will signal the end of input
/* by entering an invalid grade (not in the range 0 -> 100).
/*
/* Written by: Buzz-Barry Struck
/* Modified By: Amruth Kumar
/**********************************************/
 
#include <iostream>
#include <cstdlib>
#include <iomanip>

using namespace std;

int main()
{
   // Constants for the grading policy
   const int A_LIMIT = 91;  // A if grade >= 91
   const int B_LIMIT = 81;  // B if grade >= 81
   const int C_LIMIT = 71;  // C if grade >= 71
   const int D_LIMIT = 55;  // D if grade >= 55

   int grade;               // holds the entered grade 
   int class_size = 0;      // holds the number of students in the class
   int class_max = 0;       // holds the class maximum - initialized to min grade
   int class_min = 100;     // holds the class minimum - initialized to max grade
   int total = 0;           // holds the sum of all the grades
   float average;           // holds the value of the average grade

   int a_scorers = 0;       // holds the number of A grades in class
   int b_scorers = 0;       // holds the number of B grades in class
   int c_scorers = 0;       // holds the number of C grades in class
   int d_scorers = 0;       // holds the number of D grades in class
   int f_scorers = 0;       // holds the number of F grades in class

   cout << "Please, enter a valid grade (0 - 100)\n";  
   cin >> grade;                    // Read the grade

   while( grade >= 0 && grade <= 100 ) 
   {
      // Values used to calculate the average grade after exiting loop
      total += grade;               // add the new grade to the total
      class_size++;                 // increase the number of students

      // If the entered grade is greater than the maximum grade so far, 
      //   record it as the maximum grade
      if( grade > class_max )  
      {
         class_max = grade;
      }

      // If the entered grade is less than the minimum grade so far, 
      //   record it as the minimum grade
      if( grade < class_min )
      {                      
         class_min = grade;
      }

      // Increment the appropriate letter grade category
      if( grade >= A_LIMIT )        // increment the count of A grades
      {
         a_scorers++;
      } else if( grade >= B_LIMIT ) // increment the count of B grades
      {
         b_scorers++;
      } else if( grade >= C_LIMIT ) // increment the count of C grades
      {
         c_scorers++;
      } else if( grade >= D_LIMIT ) // increment the count of D grades
      {
         d_scorers++;
      } else                        // increment the count of F grades
      {                       
         f_scorers++;
      }

      // Reading the next grade from the user
      cout << "Please, enter the next valid grade (0 - 100)\n";  
      cin >> grade;                 // Read the grade
   }  // end of while-loop

   if( 0 == class_size )            // If no valid grades were entered
   {
      cout << "No valid grades were entered. Terminating program\n";
   }
   else
   {
      average = (float) total / class_size;   // compute the class average

      cout << class_size << " grades were entered for the class\n";
      cout << "The average grade of the class is " 
           << setiosflags( ios::fixed ) << setprecision( 1 )
           << average << endl;
      cout << "The class maximum is " << class_max << endl;
      cout << "The class minimum is " << class_min << endl;
      cout << "The grade distribution is as follows:\n";
      cout << "  A (91 - 100) - " << a_scorers << endl;
      cout << "  B (81 - 90)  - " << b_scorers << endl;
      cout << "  C (71 - 80)  - " << c_scorers << endl;
      cout << "  D (55 - 70)  - " << d_scorers << endl;
      cout << "  F (0 - 54)   - " << f_scorers << endl;
   }

   return EXIT_SUCCESS;
} // end of main