From 2dc097383cf973cbf61a2b4e0ea0eaacd8126a6e Mon Sep 17 00:00:00 2001
From: Chris <stofflees@gmail.com>
Date: Wed, 18 Dec 2024 23:21:58 +0000
Subject: [PATCH] Try with branch caching again

---
 2024/16/index.ts |   5 ---
 2024/18/index.ts | 105 ++++++++++++++++++++++++++++++-----------------
 2 files changed, 67 insertions(+), 43 deletions(-)

diff --git a/2024/16/index.ts b/2024/16/index.ts
index 526ef1e..5c4a04e 100644
--- a/2024/16/index.ts
+++ b/2024/16/index.ts
@@ -106,8 +106,6 @@ for (let y = 1; y < height - 1; y++) {
 
 let fastest: number|null = null;
 
-const scoreCache: { [key: string]: [number, Coord, Dir] } = {};
-
 const branchCache: { [key: string]: number } = {};
 
 const scores: Array<[number, Array<string>]> = [];
@@ -125,9 +123,6 @@ function getScoresAfterPosition(pos: Coord, dir: Dir, currentScore = 0, path: Ar
         } else {
             branchCache[cacheKey] = currentScore;
         }
-        if (lastBranch) {
-            scoreCache[`${lastBranch[1].x},${lastBranch[1].y}`] = [currentScore - lastBranch[0], pos, dir];
-        }
         lastBranch = [currentScore, pos];
     }
     [dir, nextDir(dir), prevDir(dir)].forEach((newDir, i) => {
diff --git a/2024/18/index.ts b/2024/18/index.ts
index 2b208ba..69d75cf 100644
--- a/2024/18/index.ts
+++ b/2024/18/index.ts
@@ -58,9 +58,27 @@ function prevDir(dir: Dir): Dir {
     return directions[i];
 }
 
-function printMap() {
+function isBranch(pos: Coord, dir: Dir): boolean {
+    const leftDir = prevDir(dir);
+    const rightDir = nextDir(dir);
+    const next = nextCoord(pos, dir);
+    const left = nextCoord(pos, leftDir);
+    const right = nextCoord(pos, rightDir);
+    const nextChar = get(next);
+    const leftChar = get(left);
+    const rightChar = get(right);
+    return nextChar === '.' && leftChar === '.'
+        || nextChar === '.' && rightChar === '.'
+        || leftChar === '.' && rightChar === '.';
+}
+
+function printMap(path: Array<Coord> = []) {
     const mapClone = map.slice().map((row: Array<string>) => row.slice());
+    path.forEach(({ x, y }) => {
+        mapClone[y][x] = 'O';
+    });
     console.log(mapClone.map((row: Array<string>) => row.join('')).join("\n"));
+    console.log("\n");
 }
 
 function nextCoord(pos: Coord, direction: Dir): Coord {
@@ -93,7 +111,6 @@ function fillDeadEnd(pos: Coord): void {
     };
 }
 printMap();
-console.log("\n");
 
 for (let y = 0; y < height; y++) {
     for (let x = 0; x < width; x++) {
@@ -110,39 +127,51 @@ for (let y = 0; y < height; y++) {
 
 printMap();
 
-//let fastest: number|null = null;
-//
-//const scoreCache: { [key: string]: [number, Coord, Dir] } = {};
-//
-//const branchCache: { [key: string]: number } = {};
-//
-//const scores: Array<number> = [];
-//
-//function getScoresAfterPosition(pos: Coord, dir: Dir, path: Array<string> = []): void {
-//    if (fastest !== null && path.length >= fastest) {
-//        return;
-//    }
-//    [dir, nextDir(dir), prevDir(dir)].forEach((newDir, i) => {
-//        const next = nextCoord(pos, newDir);
-//        const nextStr = `${next.x},${next.y}`;
-//        if (!path.includes(nextStr)) {
-//            if (next.x === width - 1 && next.y === height - 1) {
-//                if (fastest === null || path.length < fastest) {
-//                    fastest = path.length;
-//                }
-//                scores.push(path.length);
-//                return;
-//            } else if (next.x >= 0 && next. x < width && next.y >= 0 && next.y < height && get(next) === '.') {
-//                getScoresAfterPosition(next, newDir, [...path, nextStr]);
-//            }
-//        }
-//    });
-//
-//    return;
-//}
-//
-//getScoresAfterPosition({ x: 0, y: 0 }, Dir.Up, ['0,0']);
-//
-//console.log(scores);
-//const fastestScore = Math.min(...scores);
-//
+let fastest: number|null = null;
+
+const scoreCache: { [key: string]: [number, Coord, Dir] } = {};
+
+const branchCache: { [key: string]: number } = {};
+
+const scores: Array<Array<Coord>> = [];
+
+function getScoresAfterPosition(pos: Coord, dir: Dir, path: Array<Coord> = [], lastBranch: [number, Coord]|null = null): void {
+   if (fastest !== null && path.length >= fastest) {
+       return;
+   }
+    const branch = isBranch(pos, dir);
+    if (branch) {
+        const cacheKey = `${pos.x},${pos.y},${dir}`;
+        const cache = branchCache[cacheKey];
+        if (cache && cache < path.length) {
+            return;
+        } else {
+            branchCache[cacheKey] = path.length;
+        }
+        lastBranch = [path.length, pos];
+    }
+   [dir, nextDir(dir), prevDir(dir)].forEach((newDir, i) => {
+       const next = nextCoord(pos, newDir);
+       if (!path.find(({ x, y }) => next.x === x && next.y === y)) {
+           if (next.x === width - 1 && next.y === height - 1) {
+               if (fastest === null || path.length < fastest) {
+                   fastest = path.length;
+               }
+               scores.push(path);
+               return;
+           } else if (next.x >= 0 && next. x < width && next.y >= 0 && next.y < height && get(next) === '.') {
+               getScoresAfterPosition(next, newDir, [...path, next], lastBranch);
+           }
+       }
+   });
+
+   return;
+}
+
+getScoresAfterPosition({ x: 0, y: 0 }, Dir.Up, [{ x: 0, y: 0 }]);
+
+console.log(scores);
+const fastestScore = Math.min(...scores.map((p) => p.length));
+const fastestPath = scores.find((p) => p.length === fastestScore);
+printMap(fastestPath);
+console.log(fastestScore);