2023 - Day 3

2023/03/solution.ts

@@ -0,0 +1,98 @@
+const sample = await Deno.readTextFile("sample.txt");
+const input = await Deno.readTextFile("input.txt");
+
+interface Result<T> {
+  value: T;
+  line: number;
+  length: number;
+  index: number;
+}
+
+const isSymbol = (char: string): boolean =>
+  char !== undefined && isNaN(parseFloat(char)) && char !== ".";
+
+const isGear = (char: string): boolean => char === "*";
+
+const hasSurrounding = (
+  dataMap: string[],
+  { line, index, length }: Result<number>,
+  predicate: (char: string) => boolean,
+): { row: number; column: number }[] => {
+  const result: { row: number; column: number }[] = [];
+  for (let row = line - 1; row <= line + 1; row += 1) {
+    for (let column = index - 1; column < index + length + 1; column += 1) {
+      if (predicate(dataMap[row]?.[column])) result.push({ row, column });
+    }
+  }
+  return result;
+};
+
+const solvePart1 = (data: string): number => {
+  const dataMap = data
+    .split("\n")
+    .filter(Boolean);
+
+  return dataMap.map((line, index) =>
+    Array.from(
+      line.matchAll(/\d+/g),
+      (x): Result<number> => ({
+        value: parseFloat(x[0]),
+        line: index,
+        length: x[0].length,
+        index: x.index ?? -1,
+      }),
+    )
+  ).flat()
+    .reduce(
+      (sum, result) =>
+        hasSurrounding(dataMap, result, isSymbol).length
+          ? sum + result.value
+          : sum,
+      0,
+    );
+};
+
+console.log("Sample:", solvePart1(sample)); // 4361
+console.log("Input", solvePart1(input)); // 550934
+
+const solvePart2 = (data: string): number => {
+  const dataMap = data
+    .split("\n")
+    .filter(Boolean);
+
+  const numbersPerGear = dataMap.map((line, index) =>
+    Array.from(
+      line.matchAll(/\d+/g),
+      (x): Result<number> => ({
+        value: parseFloat(x[0]),
+        line: index,
+        length: x[0].length,
+        index: x.index ?? -1,
+      }),
+    )
+  ).flat()
+    .map(
+      (result) => ({
+        ...result,
+        gears: hasSurrounding(dataMap, result, isGear),
+      }),
+    ).reduce((group, result): Record<string, number[]> => {
+      result.gears.forEach((gear) => {
+        group[`${gear.row}:${gear.column}`] = [
+          ...(group[`${gear.row}:${gear.column}`] || []),
+          result.value,
+        ];
+      });
+      return group;
+    }, {} as Record<string, number[]>);
+
+  return Object.values(numbersPerGear).reduce(
+    (sum, result) =>
+      result.length > 1 ? sum + result.reduce((s, v) => s * v) : sum,
+    0,
+  );
+
+};
+
+console.log("Sample2:", solvePart2(sample)); // 467835
+console.log("Input", solvePart2(input)); // 81997870