package algs13;
import stdlib.*;
/* ***********************************************************************
 *  Compilation:  javac Stats.java
 *  Execution:    java Stats < input.txt
 *  Dependencies: Bag.java StdIn.java StdOut.java
 *
 *  Reads in a sequence of real numbers from standard input and
 *  computes their mean and standard deviation.
 *
 *  % java Stats
 *  100 99 101 120 98 107 109 81 101 90
 *  Mean:    100.60
 *  Std dev: 10.51
 *
 *************************************************************************/

public class XStats {
  public static void main(String[] args) {

    // read in numbers
    Bag<Double> numbers = new Bag<>();
    while (!StdIn.isEmpty()) {
      numbers.add(StdIn.readDouble());
    }
    int N = numbers.size();

    // compute mean
    double sum = 0.0;
    for (double x : numbers)
      sum += x;
    double mean = sum/N;

    // compute standard deviation
    sum = 0.0;
    for (double x : numbers) {
      sum += (x - mean) * (x - mean);
    }
    double std = Math.sqrt(sum/(N-1));

    StdOut.format("Mean:    %.2f\n", mean);
    StdOut.format("Std dev: %.2f\n", std);
  }
}