1 files changed, 59 insertions, 0 deletions
diff --git a/day5/index.ts b/day5/index.ts
new file mode 100644
index 0000000..1cf4a3c
--- /dev/null
+++ b/day5/index.ts
@@ -0,0 +1,59 @@
+import { Observable, of } from "rxjs";
+import { concatAll, count, filter, groupBy, map, max, mergeMap, reduce, tap } from 'rxjs/operators';
+import { ExerciseModuleFunc } from "../types";
+
+type Pair = [number, number];
+
+const getColumnAndRow = (line: string): Pair => {
+  const chars = line.split("");
+  let lo: number, hi: number;
+
+  lo = 0; hi = 127;
+  for (let i = 0; i < 7; i += 1) {
+    console.log("i:",i,"lo:",lo,"hi:",hi);
+
+    const chr = chars[i];
+    const diff = hi - lo;
+    if (chr === "F") {
+      hi = Math.floor(hi - diff / 2);
+    }
+    else if (chr === "B") {
+      lo = Math.ceil(lo + diff / 2);
+    }
+  }
+
+  const row = hi;
+
+  lo = 0; hi = 7;
+  for (let i = 0; i < 3; i += 1) {
+    console.log("i:",i,"lo:",lo,"hi:",hi);
+
+    const chr = chars[i + 7];
+    const diff = hi - lo;
+    if (chr === "L") {
+      hi = Math.floor(hi - diff / 2);
+    }
+    else if (chr === "R") {
+      lo = Math.ceil(lo + diff / 2);
+    }
+  }
+
+  const col = hi;
+  return [col, row];
+}
+
+const calcID = (pair: Pair) => pair[1] * 8 + pair[0];
+
+const day5: ExerciseModuleFunc = async (input: string) => {
+  const prom1 = of(input).pipe(
+    map(l => l.split("\n")),
+    concatAll(),
+    map(getColumnAndRow),
+    map(calcID),
+    max()
+  ).toPromise();
+
+  return Promise.all([prom1]);
+}
+
+export default day5;