day 34: 853-car-fleet

853-car-fleet/driver.cpp

@@ -0,0 +1,12 @@
+#include "soln.hpp"
+
+int main()
+{
+	int target = 12;
+	vector<int> position{10, 8, 0, 5, 3};
+	vector<int> speed{2, 4, 1, 1, 3};
+	int answer = 3;
+	Solution soln;
+	cout << "Found car fleets correctly? " << soln.test(target, position, speed, answer) << endl;
+	return 0;
+}

853-car-fleet/soln.cpp

@@ -0,0 +1,35 @@
+#include "soln.hpp"
+
+int Solution::carFleet(int target, vector<int> &position, vector<int> &speed)
+{
+	if (position.size() < 2)
+		return position.size();
+	// int fleets = position.size();
+	vector<Car> cars;
+	vector<double> slowest_times;
+	for (int i = 0; i < position.size(); i++)
+	{
+		cars.push_back(Car(position[i], speed[i]));
+	}
+	sort(
+		cars.begin(),
+		cars.end(),
+		[](const Car &lhs, const Car &rhs)
+		{
+			return lhs.start_pos < rhs.start_pos;
+		});
+	for (int i = cars.size() - 1; i >= 0; i--)
+	{
+		slowest_times.push_back((target - cars[i].start_pos) / float(cars[i].car_speed));
+		if (slowest_times.size() >= 2 && slowest_times[slowest_times.size() - 1] <= slowest_times[slowest_times.size() - 2])
+		{
+			slowest_times.pop_back();
+		}
+	}
+	return slowest_times.size();
+}
+
+bool Solution::test(int target, vector<int> &position, vector<int> &speed, int answer)
+{
+	return carFleet(target, position, speed) == answer;
+}

853-car-fleet/soln.hpp

@@ -0,0 +1,15 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution
+{
+public:
+	struct Car
+	{
+		int start_pos;
+		double car_speed;
+		Car() : start_pos(0), car_speed(0) {}
+		Car(int pos, double s) : start_pos(pos), car_speed(s) {}
+	};
+	int carFleet(int target, vector<int> &position, vector<int> &speed);
+	bool test(int target, vector<int> &position, vector<int> &speed, int answer);
+};