solve Day12 in TS

Day12/ts/solution.ts

@@ -0,0 +1,89 @@
+import * as fs from 'fs';
+import * as path from 'path';
+
+function readData(filePath: string): string[] {
+    try {
+        return fs.readFileSync(filePath, 'utf8').trim().split('\n');
+    } catch (error) {
+        console.error(`Error reading file '${filePath}': ${(error as Error).message}`);
+        process.exit(1);
+    }
+}
+
+function unfoldRecord(record: string): [string, number[]] {
+    let [dots, blockStr] = record.split(' ');
+    dots = Array(5).fill(dots).join('?');
+    const blocks = blockStr.split(',').map(Number);
+    const unfoldedBlocks = Array(5).fill(blocks).flat();
+    return [dots, unfoldedBlocks];
+}
+
+function countArrangements(dots: string, blocks: number[], i: number = 0, bi: number = 0, current: number = 0, memo: Record<string, number> = {}): number {
+    const key = `${i},${bi},${current}`;
+    if (key in memo) {
+        return memo[key];
+    }
+
+    if (i === dots.length) {
+        if (bi === blocks.length && current === 0) {
+            return 1;
+        } else if (bi === blocks.length - 1 && blocks[bi] === current) {
+            return 1;
+        } else {
+            return 0;
+        }
+    }
+
+    let ans = 0;
+    for (let c of ['.', '#']) {
+        if (dots[i] === c || dots[i] === '?') {
+            if (c === '.') {
+                if (current === 0) {
+                    ans += countArrangements(dots, blocks, i + 1, bi, 0, memo);
+                } else if (current > 0 && bi < blocks.length && blocks[bi] === current) {
+                    ans += countArrangements(dots, blocks, i + 1, bi + 1, 0, memo);
+                }
+            } else if (c === '#') {
+                ans += countArrangements(dots, blocks, i + 1, bi, current + 1, memo);
+            }
+        }
+    }
+
+    memo[key] = ans;
+    return ans;
+}
+
+function solvePuzzle(lines: string[]): number {
+    let total = 0;
+    for (let line of lines) {
+        console.log(`Processing: ${line}`);
+        let [dots, blocks] = unfoldRecord(line);
+        total += countArrangements(dots, blocks);
+    }
+    return total;
+}
+
+function testPuzzle(): void {
+    console.log("Running tests...");
+    const testLines = readData(path.join(__dirname, '../test.txt'));
+    const testResult = solvePuzzle(testLines);
+    console.log(`Test result: ${testResult}`);
+    if (testResult !== 525152) {
+        throw new Error("Test failed!");
+    }
+    console.log("Test passed.");
+}
+
+function main(): void {
+    try {
+        testPuzzle();
+        const inputLines = readData(path.join(__dirname, '../input.txt'));
+        console.log("Processing input data...");
+        const result = solvePuzzle(inputLines);
+        console.log(`Final result: ${result}`);
+    } catch (error) {
+        console.error(`An error occurred: ${(error as Error).message}`);
+    }
+}
+
+main();