Add 2021 Day 1 solutions

2018/puzzle-01-01.cc

@@ -0,0 +1,21 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2021.
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+using Int = std::int64_t;
+
+auto main() -> int
+{
+  Int value{0};
+  std::string line;
+  while (std::getline(std::cin, line)) {
+    Int incr{std::stoll(line)};
+    value += incr;
+  }
+  std::cout << "Frequency: " << value << '\n';
+  return EXIT_SUCCESS;
+}