Data commit

Task/Percolation-Mean-run-density/Java/percolation-mean-run-density.java

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+import java.util.concurrent.ThreadLocalRandom;
+
+public final class PercolationMeanRun {
+
+	public static void main(String[] aArgs) {
+		System.out.println("Running 1000 tests each:" + System.lineSeparator());
+		System.out.println(" p\tlength\tresult\ttheory\t   difference");
+		System.out.println("-".repeat(48));
+		
+	    for ( double probability = 0.1; probability <= 0.9; probability += 0.2 ) {
+	        double theory = probability * ( 1.0 - probability );
+	        int length = 100;
+	        while ( length <= 100_000 ) {
+	            double result = runTest(probability, length, 1_000);
+	            System.out.println(String.format("%.1f\t%6d\t%.4f\t%.4f\t%+.4f (%+.2f%%)",
+	            	probability, length, result, theory, result - theory, ( result - theory ) / theory * 100));
+	            length *= 10;
+	        }
+	        System.out.println();
+	    }
+
+	}
+	
+	private static double runTest(double aProbability, int aLength, int aRunCount) {
+		double count = 0.0;
+	    for ( int run = 0; run < aRunCount; run++ ) {
+	        int previousBit = 0;
+	        int length = aLength;
+	        while ( length-- > 0 ) {
+	            int nextBit = ( random.nextDouble(1.0) < aProbability ) ? 1 : 0;
+	            if ( previousBit < nextBit ) {
+	            	count += 1.0;
+	            }
+	            previousBit = nextBit;
+	        }
+	    }
+	    return count / aRunCount / aLength;
+	}
+
+	private static ThreadLocalRandom random = ThreadLocalRandom.current();
+
+}