solve for day 2 pt 1

Author: zachlysobey

day-02-deno/day-02-pt-1.ts

@@ -0,0 +1,76 @@
+export {}; // make this a module
+
+const INPUT_FILE_NAME = './input.txt';
+
+const getRawInput = async (fileName: string): Promise<string> => {
+  const rawInput = await Deno.readTextFile(fileName);
+  return rawInput;
+}
+
+type Report = number[];
+
+const parseInput = (rawInput: string): Report[] => {
+  return rawInput.trim().split("\n").reduce<Report[]>(
+    (reports, line) => {
+      const values = line.trim().split(/\s+/).map((value) => parseInt(value.trim()));
+      return reports.concat([values]);
+    },
+    [],
+  );
+}
+
+type Predicate<T> = (value: T) => boolean;
+
+const isReportSafe: Predicate<Report> = (report) => {
+  if (report[1] === report[0]) {
+    return false;
+  }
+  if (report[1] < report[0]) {
+    return report.reduce(
+      (isSafe, level, index) => {
+        if (index === 0) {
+          return isSafe;
+        }
+        const previousLevel = report[index - 1];
+        const difference = previousLevel - level;
+        return isSafe && difference > 0 && difference <= 3;
+      },
+      true,
+    );
+  }
+  if (report[1] > report[0]) {
+    return report.reduce(
+      (isSafe, level, index) => {
+        if (index === 0) {
+          return isSafe;
+        }
+        const previousLevel = report[index - 1];
+        const difference = level - previousLevel;
+        return isSafe && difference > 0 && difference <= 3;
+      },
+      true,
+    );
+  }
+  throw new Error('Invalid report');
+};
+
+
+
+const countMatchingPredicate = <T>(predicate: Predicate<T>) => {
+  return (values: T[]): number => {
+    return values.reduce(
+      (acc, value, index) => {
+        return predicate(value) ? acc + 1 : acc;
+      },
+      0
+    )
+  };
+};
+
+void async function main() {
+  const rawInput: string = await getRawInput(INPUT_FILE_NAME);
+  const parsedInput: Report[] = parseInput(rawInput);
+  const countSafeReports = countMatchingPredicate<Report>(isReportSafe);
+  const safeReportCount: number = countSafeReports(parsedInput);
+  console.log(safeReportCount);
+}();