gistfile1.txt

import edu.princeton.cs.algs4.StdRandom;
import edu.princeton.cs.algs4.StdStats;
import edu.princeton.cs.algs4.Stopwatch;

public class PercolationStats {

    private final double mean;

    private final double stddev;

    private final double confidenceLo;

    private final double confidenceHi;

    // perform trials independent experiments on an n-by-n grid
    public PercolationStats(int n, int trials) {
        if (n <= 0 || trials <= 0) {
            throw new IllegalArgumentException("n or trials is illegal");
        }
        System.out.println(String.format("n=%d, trials=%d", n, trials));
        double[] thresholds = new double[trials];
        for (int i = 0; i < trials; i++) {
            Percolation percolation = new Percolation(n);
            while (!percolation.percolates()) {
                percolation.open(StdRandom.uniform(1, n + 1), StdRandom.uniform(1, n + 1));
            }
            double threshold = (double) percolation.numberOfOpenSites() / (n * n);
            thresholds[i] = threshold;
        }
        mean = StdStats.mean(thresholds);
        stddev = trials == 1 ? Double.NaN : StdStats.stddev(thresholds);

        confidenceLo = mean - 1.96 * stddev / Math.sqrt(trials);
        confidenceHi = mean + 1.96 * stddev / Math.sqrt(trials);
    }

    // sample mean of percolation threshold
    public double mean() {
        return mean;
    }

    // sample standard deviation of percolation threshold
    public double stddev() {
        return stddev;
    }

    // low  endpoint of 95% confidence interval
    public double confidenceLo() {
        return confidenceLo;
    }

    // high endpoint of 95% confidence interval
    public double confidenceHi() {
        return confidenceHi;
    }

    // test client (described below)
    public static void main(String[] args) {
        Stopwatch stopwatch = new Stopwatch();
        PercolationStats percolationStats = new PercolationStats(Integer.parseInt(args[0]), Integer.parseInt(args[1]));
        System.out.println(String.format("mean = %f", percolationStats.mean));
        System.out.println(String.format("stddev = %f", percolationStats.stddev));
        System.out.println(String.format("95%% confidence interval = [%f, %f]", percolationStats.confidenceLo, percolationStats.confidenceHi));
        System.out.println(String.format("elapsedTime=%f", stopwatch.elapsedTime()));
    }
}