110(A,cpp): solve “Nearly Lucky Number”

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

110/a.cpp

@@ -0,0 +1,107 @@
+#include <cstdint>
+#include <iostream>
+
+namespace helpers {
+
+using namespace std;
+
+long pow(long base, long exp) {
+  if (exp == 0) return 1;
+  long half = pow(base, exp / 2);
+  if (exp % 2 == 0) return half * half;
+  return half * half * base;
+}
+
+template <typename T>
+inline void answer(const T &ans) {
+  cout << ans << "\n";
+}
+
+inline void yes() { cout << "YES\n"; }
+inline void no() { cout << "NO\n"; }
+
+}  // namespace helpers
+
+namespace {
+
+using namespace std;
+using namespace helpers;
+
+int count_lucky(uint64_t n) {
+  int lucky = 0;
+
+  for (; n > 0; n /= 10) {
+    if (n % 10 == 7 || n % 10 == 4) {
+      ++lucky;
+    }
+  }
+
+  return lucky;
+}
+
+bool nearly_lucky(uint64_t n) {
+  auto count = count_lucky(n);
+
+  for (auto c = count_lucky(n); c > 0; c /= 10) {
+    if (c % 10 != 4 && c % 10 != 7) {
+      return false;
+    }
+  }
+
+  return count != 0;
+}
+
+void solve() {
+  uint64_t n;
+  cin >> n;
+
+  if (nearly_lucky(n)) {
+    yes();
+  } else {
+    no();
+  }
+}
+
+}  // namespace
+
+// for single test case, comment out for ‹N› test cases
+#define SINGLE
+
+#ifdef TEST
+
+#include "../.common/cpp/catch_amalgamated.hpp"
+
+TEST_CASE("examples") {
+  CHECK(!nearly_lucky(40047));
+  CHECK(nearly_lucky(7747774));
+  CHECK(!nearly_lucky(1000000000000000000));
+}
+
+TEST_CASE("regression (probably platform-dependant size of ‹unsigned long›)") {
+  CHECK(nearly_lucky(4744000695826));
+}
+
+#else
+
+int main(void) {
+
+#ifdef SINGLE
+
+  solve();
+
+#else
+
+  // for multiple test cases
+  int N;
+  std::cin >> N >> std::ws;
+
+  for (auto i = 0; i < N; ++i) {
+    solve();
+  }
+
+#endif
+
+  return 0;
+}
+
+#endif