Solve 2025-11

2025/11/index.ts

@@ -0,0 +1,51 @@
+import { sumArray } from '../../utils/array.ts';
+
+function parseInput(input: string) {
+  return input.split('\n').map((row) => {
+    const [from, _to] = row.split(': ');
+
+    return { from, to: _to.split(' ') };
+  });
+}
+
+function dfs(
+  start: string,
+  target: string,
+  graph: ReturnType<typeof parseInput>,
+  memo: Map<string, number> = new Map<string, number>()
+) {
+  if (start === target) {
+    return 1;
+  }
+  if (memo.has(start)) {
+    return memo.get(start)!;
+  }
+  const val = sumArray(
+    graph
+      .find((r) => r.from === start)
+      ?.to?.map((to) => dfs(to, target, graph, memo)) || [0]
+  );
+  memo.set(start, val);
+
+  return val;
+}
+
+export function solveFirst(input: string): number {
+  const rows = parseInput(input);
+
+  return dfs('you', 'out', rows);
+}
+
+export function solveSecond(input: string): number {
+  const rows = parseInput(input);
+
+  const svr_fft = dfs('svr', 'fft', rows);
+  const fft_dac = dfs('fft', 'dac', rows);
+  const dac_out = dfs('dac', 'out', rows);
+
+  const svr_dac = dfs('svr', 'dac', rows);
+  const dac_fft = dfs('dac', 'fft', rows);
+  const fft_out = dfs('fft', 'out', rows);
+
+  return svr_fft * fft_dac * dac_out + svr_dac * dac_fft * fft_out;
+}