flip_coin_experiment.cpp

// Flip coin until we get 3 consecutive "Tail" or "Head"
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <unordered_map>

using namespace std;

enum class coin_state {head, tail};
unordered_map<coin_state, string> coin_state_ref {
		{coin_state::head, "H"},
		{coin_state::tail, "T"}
};

ostream& operator<<(ostream& os, const coin_state& cs) {
	os << coin_state_ref[cs];
}

int main() {
	srand(time(NULL)); // Should have used a better random method, but too lazy
	int no_of_experiment;
	double no_of_flip_total = 0;
	cout << "How many times do you want to do experiment? ";
	cin >> no_of_experiment;
	for (int run = 1; run <= no_of_experiment; ++run) {
		cout << "========= Experiment number: " << run << " =========\n";
		int no_of_flip = 0;
		for (int count_tail = 0, count_head = 0; count_head < 3 && count_tail < 3;) {
			++no_of_flip;
			auto state = rand() % 2 == 0 ? coin_state::head : coin_state::tail;
			cout << state << " ";
			if (state == coin_state::tail) {
				++count_tail;
				count_head = 0;
			} else {
				++count_head;
				count_tail = 0;
			}
		}
		no_of_flip_total += no_of_flip;
		cout << "\nNeed " << no_of_flip << " flip(s)\n";
	}
	cout << "==================\nAverage: " << no_of_flip_total / no_of_experiment << " flip(s)";

	return 0;
}