Add solution to 'a lot' of problems

Easy/climbing-stairs/solution.cpp

@@ -0,0 +1,17 @@
+#include <vector>
+
+class Solution {
+public:
+    int climbStairs(int n) {
+        if (n == 0) {
+            return 0;
+        }
+
+        std::vector<int> shiftTwoFibo{1, 2};
+        for (int i = 2; i < n; ++i) {
+            shiftTwoFibo.push_back(shiftTwoFibo[i - 1] + shiftTwoFibo[i - 2]);
+        }
+
+        return shiftTwoFibo[n - 1];
+    }
+};