Day 19 and 20

2024/19/index.ts

@@ -0,0 +1,46 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8').split("\n");
+
+const towels: Array<string> = input[0].split(', ');
+
+const shortestTowel = Math.min(...towels.map((t: string) => t.length));
+const longestTowel = Math.max(...towels.map((t: string) => t.length));
+
+const designs = input.slice(2);
+
+let possible = 0;
+
+let permSum = 0;
+
+let patternMap: { [key: string]: number } = {};
+
+function canBeDone(pattern: string): number {
+    if (Object.hasOwn(patternMap, pattern)) {
+        return patternMap[pattern];
+    }
+    let perms = 0;
+    towels.forEach((t) => {
+        if (t === pattern) {
+            patternMap[pattern] = 1;
+            perms++;
+        } else if (pattern.startsWith(t)) {
+            const subPerms = canBeDone(pattern.substring(t.length));
+            perms += subPerms;
+        }
+    });
+    patternMap[pattern] = perms;
+    return perms;
+}
+
+designs.forEach((d: string, i: number)=> {
+    patternMap = {};
+    console.log(Math.floor(i / designs.length * 100));
+    const designPerms = canBeDone(d);
+    if (designPerms) {
+        possible++;
+        permSum += designPerms;
+    }
+});
+
+console.log(possible, permSum);

2024/20/index.ts

@@ -0,0 +1,107 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+interface Coord {
+    x: number,
+    y: number,
+};
+
+enum Dir {
+    Up,
+    Right,
+    Down,
+    Left,
+};
+
+const map: Array<Array<string>> = input.split("\n").map((row: string) => row.split(''));
+
+const width = map[0].length;
+const height = map.length;
+
+const startIndex = input.indexOf('S');
+let startPos = { x: startIndex % (width + 1), y: Math.floor(startIndex / height) };
+
+function get(pos: Coord): string {
+    if (map[pos.y] && map[pos.y][pos.x]) {
+        return map[pos.y][pos.x];
+    }
+    return '#';
+}
+
+function set(pos: Coord, val: string): void {
+    map[pos.y][pos.x] = val;
+}
+
+function nextDir(dir: Dir): Dir {
+    const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
+    const i = (directions.indexOf(dir) + 1) % directions.length;
+    return directions[i];
+}
+function prevDir(dir: Dir): Dir {
+    const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
+    const i = directions.indexOf(dir) - 1;
+    if (i < 0) {
+        return directions[directions.length - 1];
+    }
+    return directions[i];
+}
+
+function nextCoord(pos: Coord, direction: Dir): Coord {
+    return direction === Dir.Up ? { x: pos.x, y: pos.y - 1 }
+        : (direction === Dir.Right ? { x: pos.x + 1, y: pos.y }
+            : (direction === Dir.Down ? { x: pos.x, y: pos.y + 1 } : { x: pos.x - 1, y: pos.y })
+        );
+}
+
+const shortCuts: Array<number> = [];
+
+const pathCoords: Array<Coord> = [startPos];
+
+const cheatTime = 20;
+const minShortCut = 100;
+
+let speedMap: { [key: string]: number } = {};
+
+function findShortCuts(pos: Coord): void {
+    for (let i = 0; i < pathCoords.length - minShortCut; i++) {
+        const possibleSC = pathCoords[i];
+        const dx = possibleSC.x - pos.x;
+        const dy = possibleSC.y - pos.y;
+        const cheatLength = Math.abs(dx) + Math.abs(dy);
+        if (cheatLength <= cheatTime) {
+            const shortCutLength = pathCoords.length - i - cheatLength;
+            if (shortCutLength >= minShortCut) {
+                shortCuts.push(shortCutLength);
+            }
+        }
+    }
+}
+
+for (let dir of [Dir.Up, Dir.Right, Dir.Down, Dir.Left]) {
+    if (get(nextCoord(startPos, dir)) === '.') {
+        let pos = startPos;
+        loop:
+        while (true) {
+            for (let newDir of [dir, nextDir(dir), prevDir(dir)]) {
+                const next = nextCoord(pos, newDir);
+                const nextStr = `${next.x},${next.y}`;
+                const nextChar = get(next);
+                if (nextChar === 'E') {
+                    findShortCuts(next);
+                    pathCoords.push(next);
+                    break loop;
+                } else if (nextChar === '.') {
+                    findShortCuts(next);
+                    pathCoords.push(next);
+                    pos = next;
+                    dir = newDir;
+                    break;
+                }
+            };
+        }
+        break;
+    }
+}
+
+console.log(shortCuts.length);