A-M baby

Task/Knuths-algorithm-S/Java/knuths-algorithm-s-1.java

@@ -0,0 +1,37 @@
+import java.util.*;
+
+class SOfN<T> {
+    private static final Random rand = new Random();
+
+    private List<T> sample;
+    private int i = 0;
+    private int n;
+    public SOfN(int _n) {
+	n = _n;
+	sample = new ArrayList<T>(n);
+    }
+    public List<T> process(T item) {
+	i++;
+	if (i <= n) {
+            sample.add(item);
+	} else if (rand.nextInt(i) < n) {
+	    sample.set(rand.nextInt(n), item);
+	}
+	return sample;
+    }
+}
+
+public class AlgorithmS {
+    public static void main(String[] args) {
+	int[] bin = new int[10];
+	for (int trial = 0; trial < 100000; trial++) {
+	    SOfN<Integer> s_of_n = new SOfN<Integer>(3);
+	    List<Integer> sample = null;
+	    for (int i = 0; i < 10; i++)
+		sample = s_of_n.process(i);
+	    for (int s : sample)
+		bin[s]++;
+	}
+	System.out.println(Arrays.toString(bin));
+    }
+}