day 7: 70-climbing-stairs

70-climbing-stairs/driver.cpp

@@ -0,0 +1,10 @@
+#include "soln.hpp"
+
+int main()
+{
+	int n = 9;
+	int answer = 55;
+	Solution soln;
+	cout << "Found steps correctly? " << soln.test(n, answer) << endl;
+	return 0;
+}

70-climbing-stairs/soln.cpp

@@ -0,0 +1,25 @@
+#include "soln.hpp"
+
+int Solution::climbStairs(int n)
+{
+	if (n < 4)
+		return n;
+
+	long minus_one = 3;
+	long minus_two = 2;
+	long steps = 0;
+
+	for (int i = 3; i < n; i++)
+	{
+		// climb one
+		steps = minus_one + minus_two;
+		minus_two = minus_one;
+		minus_one = steps;
+	}
+
+	return steps;
+}
+
+bool Solution::test(int n, long answer)	{
+	return climbStairs(n) == answer;
+}

70-climbing-stairs/soln.hpp

@@ -0,0 +1,7 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution	{
+	public:
+		int climbStairs(int n);
+		bool test(int n, long answer);
+};