Data commit

Task/100-prisoners/Java/100-prisoners.java

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+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class Main {
+    private static boolean playOptimal(int n) {
+        List<Integer> secretList = IntStream.range(0, n).boxed().collect(Collectors.toList());
+        Collections.shuffle(secretList);
+
+        prisoner:
+        for (int i = 0; i < secretList.size(); ++i) {
+            int prev = i;
+            for (int j = 0; j < secretList.size() / 2; ++j) {
+                if (secretList.get(prev) == i) {
+                    continue prisoner;
+                }
+                prev = secretList.get(prev);
+            }
+            return false;
+        }
+        return true;
+    }
+
+    private static boolean playRandom(int n) {
+        List<Integer> secretList = IntStream.range(0, n).boxed().collect(Collectors.toList());
+        Collections.shuffle(secretList);
+
+        prisoner:
+        for (Integer i : secretList) {
+            List<Integer> trialList = IntStream.range(0, n).boxed().collect(Collectors.toList());
+            Collections.shuffle(trialList);
+
+            for (int j = 0; j < trialList.size() / 2; ++j) {
+                if (Objects.equals(trialList.get(j), i)) {
+                    continue prisoner;
+                }
+            }
+
+            return false;
+        }
+        return true;
+    }
+
+    private static double exec(int n, int p, Function<Integer, Boolean> play) {
+        int succ = 0;
+        for (int i = 0; i < n; ++i) {
+            if (play.apply(p)) {
+                succ++;
+            }
+        }
+        return (succ * 100.0) / n;
+    }
+
+    public static void main(String[] args) {
+        final int n = 100_000;
+        final int p = 100;
+        System.out.printf("# of executions: %d\n", n);
+        System.out.printf("Optimal play success rate: %f%%\n", exec(n, p, Main::playOptimal));
+        System.out.printf("Random play success rate: %f%%\n", exec(n, p, Main::playRandom));
+    }
+}