#include <iostream>
#include <fstream>
#include <string>
#include <cmath>

using namespace std;

/****************************************************
main() reads in numbers from a file,
then compute the min, max, average, and std deviation.
******************************************************/

int* readArrayFromFile(string filename, int &N);
void calcMinAndMax(int *array, int N, int &min, int &max);
double  calcAverage  (int *array, int N);
double  calcStddev   (int *array, int N, double average);

int main() {

    // Read the array 
    int N;
    int* array = readArrayFromFile("numbers.txt", N);
    cout << "Got array of size: " << N << endl;

    // Get the min and max
    int min, max;
    calcMinAndMax(array, N, min, max);
    cout << "Min is " << min << endl;
    cout << "Max is " << max << endl;

    // Compute the average
    double average;
    average = calcAverage(array, N);
    cout << "Average is " << average << endl;

    // Compute standard deviation
    cout << "Std. deviation is " << calcStddev(array, N, average) << endl;

    return 0;
}



// function readArrayFromFile()
// Reads from a file that looks like this
//    N = 3
//    DATA:	
//    67
//    61
//    82
int* readArrayFromFile(string filename, int &N) 
{
    ifstream fin(filename.c_str());

    // Get header info
    string junk;
    fin >> junk >> junk >> N >> junk;

    // Make the array
    int *array = new int[N];

    // Read data in
    for (int i=0; i<N; i++)
    {
        fin >> array[i];
    }
    return array;
}

// Calculate min and max value of array
void calcMinAndMax(int *array, int N, int &min, int &max)
{
    // defaults
    min = array[0];
    max = array[0];

    // check whole array 
    for (int i=0; i<N; i++) 
    {
        int val = array[i];
        if (val < min)
        {
            min = val;
        }
        if (val > max)
        {
            max = val;
        }
    }
}

double  calcAverage  (int *array, int N) 
{
    int sum = 0;
    for (int i=0; i<N; i++)
    {
        sum += array[i];
    }
    return double(sum)/N;
}

/* Compute standard deviation of the array,
Recall that the standard deviation is

      ______________________
     / -- n   
    /  \     (xi - ave)^2
   /    |    ------------
  /    /        n - 1
\/     -- i = 1
*/
double  calcStddev   (int *array, int N, double average)
{ 
    double sum = 0;
    for (int i=0; i<N; i++)
    {
        double term = (array[i] - average);
        sum += (term * term) / double(N-1);
    }
    return sqrt(sum);
}