Data commit

Task/Percolation-Site-percolation/Java/percolation-site-percolation.java

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+import java.util.concurrent.ThreadLocalRandom;
+
+public final class PercolationSite {
+
+	public static void main(String[] aArgs) {		
+		final int rowCount = 15;
+		final int colCount = 15;
+		final int testCount = 1_000;
+		
+		Grid grid = new Grid(rowCount, colCount, 0.5);
+		grid.percolate();
+		grid.display();
+		
+		System.out.println("Proportion of " + testCount + " tests that percolate through the grid:");
+	    for ( double probable = 0.0; probable <= 1.0; probable += 0.1 ) {
+	    	int percolationCount = 0;
+	        for ( int test = 0; test < testCount; test++) {
+	            Grid testGrid = new Grid(rowCount, colCount, probable);
+	            if ( testGrid.percolate() ) {
+	            	percolationCount += 1;
+	            }
+	        }
+	        double percolationProportion = (double) percolationCount / testCount;
+	        System.out.println(String.format("%s%.1f%s%.4f", " p = ", probable, ": ", percolationProportion));
+	    }
+	}
+
+}
+
+final class Grid {
+	
+	public Grid(int aRowCount, int aColCount, double aProbability) {
+		createGrid(aRowCount, aColCount, aProbability);
+	}
+	
+	public boolean percolate() {
+		for ( int x = 0; x < table[0].length; x++ ) {
+			if ( pathExists(x, 0) ) {
+				return true;
+			}
+		}
+		return false;
+	}
+	
+	public void display() {
+	    for ( int col = 0; col < table.length; col++ ) {
+	        for ( int row = 0; row < table[0].length; row++ ) {
+	            System.out.print(" " + table[col][row]);
+	        }
+	        System.out.println();
+	    }
+	    System.out.println();
+	}
+	
+	private boolean pathExists(int aX, int aY) {		
+	    if ( aY < 0 || aX < 0 || aX >= table[0].length || table[aY][aX].compareTo(FILLED) != 0 ) {
+	    	return false;
+	    }
+	    table[aY][aX] = PATH;
+	    if ( aY == table.length - 1 ) {
+	    	return true;
+	    }
+	    return pathExists(aX, aY + 1) || pathExists(aX + 1, aY) || pathExists(aX - 1, aY) || pathExists(aX, aY - 1);
+	}
+	
+	private void createGrid(int aRowCount, int aColCount, double aProbability) {
+		table = new String[aRowCount][aColCount];		
+		for ( int col = 0; col < aRowCount; col++ ) {
+			for ( int row = 0; row < aColCount; row++ ) {
+				table[col][row] = ( RANDOM.nextFloat(1.0F) < aProbability ) ? FILLED: EMPTY;
+			}
+		}	
+	}
+	
+	private String[][] table;
+	
+	private static final String EMPTY = " ";
+	private static final String FILLED = ".";
+	private static final String PATH = "#";
+	private static final ThreadLocalRandom RANDOM = ThreadLocalRandom.current();
+	
+}