#include <iostream>
#include <string>
using namespace std;

const int NUM_EXAMS = 3;
struct student {
  string name;
  double ave;
  char grade;
  int examScores[NUM_EXAMS];
};

// function prototypes
void  readAllStu(student[], int&, int);
void readOneStu(student&, int);
void calcStuAverage(student[], int, int);
void calcClassAverage(student[], int, double[], int);
void display(student[], int, double[], int);
void assignGrade(student[], int, int[]);
double calcAve(int[], int);

int main() {
  const int SIZE = 20;
  student cis67[SIZE];
  const int NUM_EXAMS = 3;
  double classAve[NUM_EXAMS];
  int minScore[4] = {90, 80, 70, 60};
  int numStu;

  // Read all student data
  readAllStu(cis67, numStu, NUM_EXAMS);

  // Calculate each student's exam ave
  calcStuAverage(cis67, numStu, NUM_EXAMS);

  // Calculate class ave for each exam
  calcClassAverage(cis67, numStu, classAve, NUM_EXAMS);

  // Assign a letter grade.
  assignGrade(cis67, numStu, minScore);

  // Display all results
  display(cis67, numStu, classAve, NUM_EXAMS);
  // cout << cis67[0].name << cis67[0].ave << endl;
  // cout << classAve[0] << " " << classAve[1] << " " << classAve[2] << endl;

  return 0;
}

void assignGrade(student cis67[], int numStu, int minScore[4])
{
  for (int nextStu = 0; nextStu < numStu; nextStu++)
  {
    if (cis67[nextStu].ave >= minScore[0])
       cis67[nextStu].grade = 'A';
    else if (cis67[nextStu].ave >= minScore[1])
       cis67[nextStu].grade = 'B';
    else if (cis67[nextStu].ave >= minScore[2])
       cis67[nextStu].grade = 'C'; 
    else if (cis67[nextStu].ave >= minScore[3])
       cis67[nextStu].grade = 'D';
    else   
        cis67[nextStu].grade = 'F';
 }
}

 
void readOneStu(student& aStu, int NUM_EXAMS)
{
  cout << "Enter name and " << NUM_EXAMS << " exams" << endl;
  cin >> aStu.name;
  for (int i = 0; i < NUM_EXAMS; i++)
	 cin >> aStu.examScores[i];
  cin.ignore(20, '\n');  // skip end of line
}

void  readAllStu(student cis67[], int& numStu, int NUM_EXAMS)
{
	cout << "How many students > ";
	cin >> numStu;
	for (int i = 0; i < numStu; i++)
	  readOneStu(cis67[i], 	NUM_EXAMS);
}

void calcStuAverage(student cis67[], int numStu, int NUM_EXAMS)
{
  for (int nextStu = 0; nextStu < numStu; nextStu++)
  {
	  cis67[nextStu].ave = 
               calcAve(cis67[nextStu].examScores, NUM_EXAMS);
  }
}

double calcAve(int x[], int size) 
{
  int sum = 0;
  for (int i = 0; i < size; i++)
    sum += x[i];
  return (double) sum / size;
}


void calcClassAverage(student cis67[], int numStu, double classAve[], 
int NUM_EXAMS)
{
	int sum;
	for (int nextExam = 0; nextExam < NUM_EXAMS; nextExam++)
	{
		sum = 0;
		for (int nextStu = 0; nextStu < numStu; nextStu++)
		  sum += cis67[nextStu].examScores[nextExam];
		classAve[nextExam] = (double) sum / numStu;
	}
}


void displayOneStu(student aStu, int NUM_EXAMS) 
{
   cout << aStu.name << "  ";
   for (int i = 0; i < NUM_EXAMS; i++)
      cout << aStu.examScores[i] << "  ";
   cout << aStu.ave << "  " << aStu.grade << endl;
}


void display(student cis67[], int numStu, double classAve[], int NUM_EXAMS)
{
   for (int nextStu = 0; nextStu < numStu; nextStu++)
   {
      displayOneStu(cis67[nextStu], NUM_EXAMS);
   }
   cout << "average  ";
   for (int nextExam = 0; nextExam < NUM_EXAMS; nextExam++)
     cout << classAve[nextExam] << "  ";
   cout << endl;
}