Algorithms-I : 1-Percolation: app PercolationStats.java

1 files changed, 72 insertions, 0 deletions

diff --git a/Algorithms/Part-I/1-Percolation/PercolationStats.java b/Algorithms/Part-I/1-Percolation/PercolationStats.java
new file mode 100644
index 0000000..9f7a0e9
--- /dev/null
+++ b/Algorithms/Part-I/1-Percolation/PercolationStats.java
@@ -0,0 +1,72 @@
+/* vim: set expandtab tabstop=4 shiftwidth=4 : */
+
+public class PercolationStats
+{
+    private double[] results;
+    private double mean;
+    private double stddev;
+    private int N;
+
+    // perform T independent computational experiments on an N-by-N grid
+    public PercolationStats(int N, int T)
+    {
+        if (N < 1 || T < 1)
+            throw new java.lang.IllegalArgumentException("received value < 1");
+        this.N = N;
+        results = new double[T];
+        int n = N*N;
+        for (int t = 0; t < T; t++)
+        {
+            double c = 0;
+            Percolation p = new Percolation(N);
+            do
+            {
+                int i = StdRandom.uniform(1, N+1);
+                int j = StdRandom.uniform(1, N+1);
+                if (!p.isOpen(i, j)) {
+                    p.open(i, j);
+                    c += 1;
+                }
+            }
+            while(!p.percolates());
+            results[t] = c / n;
+        }
+        mean = StdStats.mean(results);
+        stddev = StdStats.stddev(results);
+    }
+
+    // sample mean of percolation threshold
+    public double mean()
+    {
+        return mean;
+    }
+
+    // sample standard deviation of percolation threshold
+    public double stddev()
+    {
+        return stddev;
+    }
+
+    // returns lower bound of the 95% confidence interval
+    public double confidenceLo()
+    {
+        return mean - 1.96*stddev/Math.sqrt(N);
+    }
+
+    // returns upper bound of the 95% confidence interval
+    public double confidenceHi()
+    {
+        return mean + 1.96*stddev/Math.sqrt(N);
+    }
+
+    // test client
+    public static void main(String[] args) {
+        int N = Integer.parseInt(args[0]);
+        int T = Integer.parseInt(args[1]);
+        PercolationStats stats = new PercolationStats(N, T);
+        System.out.printf("mean                    = %.16f\n", stats.mean());
+        System.out.printf("stddev                  = %.16f\n", stats.stddev());
+        System.out.printf("95%% confidence interval = %.16f, %.16f\n\n",
+                stats.confidenceLo(), stats.confidenceHi());
+    }
+}