Add day 17 of year 2024 🤶

letelete · Dec 17, 2024 · 3fa58fa · 3fa58fa
1 parent 4647b41
commit 3fa58fa
Show file tree

Hide file tree

Showing 3 changed files with 16 additions and 21 deletions.
diff --git a/2024/README.md b/2024/README.md
@@ -19,12 +19,12 @@
 | [13](./days/day-13) | ![gold-star](../assets/star-gold.svg) ![gold-star](../assets/star-gold.svg) | 1.27ms \| 0.15ms | [Open on AoC](https://adventofcode.com/2024/day/13) |
 | [14](./days/day-14) | ![gold-star](../assets/star-gold.svg) ![gold-star](../assets/star-gold.svg) | 0.19ms \| 645.41ms | [Open on AoC](https://adventofcode.com/2024/day/14) |
 | [16](./days/day-16) | ![gold-star](../assets/star-gold.svg) ![gold-star](../assets/star-gold.svg) | 10.97ms \| 8.328s | [Open on AoC](https://adventofcode.com/2024/day/16) |
-| [17](./days/day-17) | ![gold-star](../assets/star-gold.svg) ![gold-star](../assets/star-gold.svg) | 6.09ms \| 2.35ms | [Open on AoC](https://adventofcode.com/2024/day/17) |
+| [17](./days/day-17) | ![gold-star](../assets/star-gold.svg) ![gold-star](../assets/star-gold.svg) | 11.14ms \| 5.96ms | [Open on AoC](https://adventofcode.com/2024/day/17) |
 
 > Autogenerated using [Custom GitHub Action Workflow](https://github.com/letelete/advent-of-code/blob/496913f895327f7755c5f03117730239d2b912eb/.github/workflows/update-year-readme.yml).
 > Made by [Bruno Kawka](https://kawka.me).
 
-> Last update at Tue Dec 17 11:05:30 UTC 2024
+> Last update at Tue Dec 17 11:09:32 UTC 2024
 
 ## AoC Bash Utility
 

diff --git a/2024/days/day-17/README.md b/2024/days/day-17/README.md
@@ -8,7 +8,7 @@ Memory: 18.00 GB
 
 ## Answer
 
-| part | time (~) | μs                 |
-| ---- | -------- | ------------------ |
-| 1    | 6.09ms   | 6.088292000000003  |
-| 2    | 2.35ms   | 2.3469580000000008 |
+| part | time (~) | μs                |
+| ---- | -------- | ----------------- |
+| 1    | 11.50ms  | 11.49562499999999 |
+| 2    | 5.88ms   | 5.879374999999996 |
diff --git a/2024/days/day-17/main.js b/2024/days/day-17/main.js
@@ -80,32 +80,27 @@ function Computer({ reg: { a, b, c }, verbose }) {
 }
 
 function findMinAToOutputSelf({ reg: { b, c }, program }) {
-  const cache = new Map();
-
-  const lookup = (lowerBound, ptr) => {
-    const hash = `${lowerBound},${ptr}`;
-    if (cache.has(hash)) {
-      return cache.get(hash);
-    }
+  // If a1 >= a0 * 8, cmp.run with a=a1 retains the last digit of cmp.out for cmp.run with a=a0.
+  const lowerBound = (a) => 8 * a;
+  const upperBound = (a) => 8 * (a + 1) - 1;
 
+  const lookup = (a, ptr) => {
     if (ptr < 0) {
-      return lowerBound;
+      return a;
     }
 
-    for (let a = lowerBound * 8; a < (lowerBound + 1) * 8; ++a) {
-      const cmp = Computer({ reg: { a, b, c } });
+    for (let _a = lowerBound(a); _a <= upperBound(a); ++_a) {
+      const cmp = Computer({ reg: { a: _a, b, c } });
       cmp.run(program);
 
       if (cmp.state.out[0] === program[ptr]) {
-        const match = lookup(a, ptr - 1);
-        if (match >= 0) {
-          cache.set(hash, match);
-          return match;
+        const _alookup = lookup(_a, ptr - 1);
+        if (_alookup >= 0) {
+          return _alookup;
         }
       }
     }
 
-    cache.set(hash, -1);
     return -1;
   };