Birthday problem: Difference between revisions

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 So, for example, we need a group of 88 to have at least a 50% chance of 3 people in the group having the same birthday in a year of 365 days.  And, in that case, the simulated probability was 51.0737%
+=={{header|Java}}==
+Translation of [[Birthday_problem#Python|Python]] via [[Birthday_problem#D|D]]
+{{works with|Java|8}}
+<lang java>import static java.util.Arrays.stream;
+import java.util.Random;
+public class Test {
+    static double equalBirthdays(int nSharers, int groupSize, int nRepetitions) {
+        Random rand = new Random(1);
+        int eq = 0;
+        for (int i = 0; i < nRepetitions; i++) {
+            int[] group = new int[365];
+            for (int j = 0; j < groupSize; j++)
+                group[rand.nextInt(group.length)]++;
+            eq += stream(group).anyMatch(c -> c >= nSharers) ? 1 : 0;
+        }
+        return (eq * 100.0) / nRepetitions;
+    }
+    public static void main(String[] a) {
+        int groupEst = 2;
+        for (int sharers = 2; sharers < 6; sharers++) {
+            // Coarse.
+            int groupSize = groupEst + 1;
+            while (equalBirthdays(sharers, groupSize, 100) < 50.0)
+                groupSize++;
+            // Finer.
+            int inf = (int) (groupSize - (groupSize - groupEst) / 4.0);
+            for (int gs = inf; gs < groupSize + 999; gs++) {
+                double eq = equalBirthdays(sharers, groupSize, 250);
+                if (eq > 50.0) {
+                    groupSize = gs;
+                    break;
+                }
+            }
+            // Finest.
+            for (int gs = groupSize - 1; gs < groupSize + 999; gs++) {
+                double eq = equalBirthdays(sharers, gs, 50_000);
+                if (eq > 50.0) {
+                    groupEst = gs;
+                    System.out.printf("%d independent people in a group of "
+                            + "%s share a common birthday. (%5.1f)%n",
+                            sharers, gs, eq);
+                    break;
+                }
+            }
+        }
+    }
+}</lang>
+<pre>2 independent people in a group of 23 share a common birthday. ( 50,6)
+independent people in a group of 87 share a common birthday. ( 50,4)
+independent people in a group of 187 share a common birthday. ( 50,1)
+independent people in a group of 314 share a common birthday. ( 50,2)</pre>
 =={{header|Lasso}}==