chore(cpp): update skeleton

Signed-off-by: Matej Focko <me@mfocko.xyz>

.common/cpp/skeleton.cpp

@@ -1,18 +1,28 @@
 #include <iostream>
 
-namespace {
+namespace helpers {
 
 using namespace std;
 
 long pow(long base, long exp) {
-  if (exp == 0)
-    return 1;
+  if (exp == 0) return 1;
   long half = pow(base, exp / 2);
-  if (exp % 2 == 0)
-    return half * half;
+  if (exp % 2 == 0) return half * half;
   return half * half * base;
 }
 
+template <typename T>
+inline void answer(const T &ans) {
+  cout << ans << "\n";
+}
+
+}  // namespace helpers
+
+namespace {
+
+using namespace std;
+using namespace helpers;
+
 void solve() {
   // TODO
 }
@@ -22,7 +32,15 @@ void solve() {
 // for single test case, comment out for ‹N› test cases
 #define SINGLE
 
-#ifndef TEST
+#ifdef TEST
+
+#include "../.common/cpp/catch_amalgamated.hpp"
+
+TEST_CASE("examples") {
+  // TODO
+}
+
+#else
 
 int main(void) {
 
@@ -45,10 +63,4 @@ int main(void) {
   return 0;
 }
 
-#else
-
-#include "../.common/cpp/catch_amalgamated.hpp"
-
-// TODO
-
-#endif
+#endif