From 91527e416a282aaa3872e7cdc6235cd1fb545a25 Mon Sep 17 00:00:00 2001
From: Benjamin Kraft <benjamin.kraft@online.de>
Date: Thu, 30 Jun 2022 18:45:33 +0200
Subject: [PATCH] 100 prisoners

---
 CMakeLists.txt |  6 ++++++
 main.cpp       | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 main.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..79dc9bd
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.22)
+project(100_Prisoners)
+
+set(CMAKE_CXX_STANDARD 23)
+
+add_executable(100_Prisoners main.cpp)
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..c0229ec
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,47 @@
+#include <iostream>
+#include <vector>
+#include <random>
+
+using std::cout, std::endl;
+
+int main() {
+	const int PRISONER_COUNT = 100;
+	const int N = 1000000;
+
+
+	std::random_device rd;
+	std::default_random_engine rng(rd());
+
+	std::vector<int> numbers;
+	for (int i = 0; i < PRISONER_COUNT; i++)
+		numbers.push_back(i);
+
+	auto runExperiment = [](const std::vector<int> &numbers){
+		for (int j = 0; j < PRISONER_COUNT; j++){
+			int nextBox = j;
+			bool success = false;
+			for (int i = 0; i < PRISONER_COUNT / 2; i++){
+				nextBox = numbers[nextBox];
+				if (nextBox == j){
+
+					if (i == PRISONER_COUNT / 2 - 1)
+						return true;
+
+					success = true;
+					break;
+				}
+			}
+			if (!success) return false;
+		}
+		return true;
+	};
+
+	int success = 0;
+	for (int i = 0; i < N; i++){
+		std::shuffle(numbers.begin(), numbers.end(), rng);
+		if (runExperiment(numbers)) success++;
+	}
+	cout << double(success) / N << endl;
+
+	return 0;
+}