feat: implement frequency calculation from input file

Author: MattCarolus10

Sprint-1/stretch/aoc-2018-day1/solution.js

@@ -0,0 +1,12 @@
+const fs = require("fs");
+const lines = fs.readFileSync("input.txt", "utf8").split("\n");
+
+let frequency = 0;
+
+for (const line of lines) {
+  if (line !== "") {
+    frequency += Number(line);
+  }
+}
+console.log(frequency);
+