2022 Day 3 Part 1

2022/day3.js

@@ -0,0 +1,36 @@
+const readline = require('readline');
+const fs = require('fs');
+
+function calculate_score(input) {
+    if ('a' <= input && input <= 'z') {
+        return input.charCodeAt(0) - 'a'.charCodeAt(0) + 1;
+    } else if ('A' <= input && input <= 'Z') {
+        return input.charCodeAt(0) - 'A'.charCodeAt(0) + 27;
+    } else {
+        throw `Invalid character '${input}'`
+    }
+}
+
+async function puzzle() {
+
+    const lines = readline.createInterface({
+        input: fs.createReadStream('day3.input'),
+    });
+
+    var score = 0;
+    for await (const line of lines) {
+        const mid = line.length / 2;
+        const first = line.substring(0, mid);
+        const second  = new Set(line.substring(mid));
+
+        for (const character of first) {
+            if (second.has(character)) {
+                score += calculate_score(character);
+                break;
+            }
+        }
+    }
+    console.log(`Part 1: Score ${score}`);
+}
+
+puzzle();