Day 21 Part 1

2024-12-22 11:36:29 +00:00
parent 471c797821
commit 4574a0f268
1 changed files with 134 additions and 0 deletions
--- a/2024/21/index.ts
+++ b/2024/21/index.ts
@@ -0,0 +1,134 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+interface Coord {
+    x: number,
+    y: number,
+};
+
+const keyPadMap: { [key: string]: Coord } = {
+    A: { x: 2, y: 3 },
+    '0': { x: 1, y: 3 },
+    '1': { x: 0, y: 2 },
+    '2': { x: 1, y: 2 },
+    '3': { x: 2, y: 2 },
+    '4': { x: 0, y: 1 },
+    '5': { x: 1, y: 1 },
+    '6': { x: 2, y: 1 },
+    '7': { x: 0, y: 0 },
+    '8': { x: 1, y: 0 },
+    '9': { x: 2, y: 0 },
+};
+
+const directionMap: { [key: string]: Coord } = {
+    '<': { x: 0, y: 1 },
+    'v': { x: 1, y: 1 },
+    '>': { x: 2, y: 1 },
+    '^': { x: 1, y: 0 },
+    A: { x: 2, y: 0 },
+};
+
+const permsMap: { [key: string]: Array<string> } = {
+    '0,0': [],
+    '0,1': ['Y'],
+    '1,0': ['X'],
+    '1,1': ['XY', 'YX'],
+    '2,0': ['XX'],
+    '2,1': ['XXY', 'YXX'],
+    '2,2': ['XXYY', 'YYXX'],
+    '0,2': ['YY'],
+    '1,2': ['XYY', 'YYX'],
+    '0,3': ['YYY'],
+    '1,3': ['XYYY', 'YYYX'],
+    '2,3': ['XXYYY', 'YYYXX'],
+};
+
+function buttonsToPressCoords(from: Coord, to: Coord, forbidden: Coord): Array<string> {
+    const dx = to.x - from.x;
+    const dy = to.y - from.y;
+
+    if (dx === 0 && dy === 0) {
+        return ['A'];
+    }
+
+    const buttons: Array<Array<string>> = [];
+
+    const xArrow = dx < 0 ? '<' : '>';
+    const yArrow = dy < 0 ? '^' : 'v';
+
+    const absX = Math.abs(dx);
+    const absY = Math.abs(dy);
+    const perms: Array<string> = permsMap[`${absX},${absY}`];
+
+    return perms.map((seq: string) => {
+        return seq.split('').map((xy) => xy === 'X' ? xArrow : yArrow);
+    }).filter((seq: Array<string>) => {
+        let coord = { x: from.x, y: from.y };
+        for (let arrow of seq) {
+            if (arrow === '<') {
+                coord.x--;
+            } else if (arrow === '>') {
+                coord.x++
+            } else if (arrow === '^') {
+                coord.y--;
+            } else {
+                coord.y++;
+            }
+            if (coord.x === forbidden.x && coord.y === forbidden.y) {
+                return false;
+            }
+        }
+        return true;
+    }).map((seq) => [...seq, 'A'].join(''));
+}
+
+function buttonsForSequence(start: Coord, seq: string, keyMap: { [key: string]: Coord }): Array<string> {
+    let allPerms = [];
+    const buttons = [];
+    for (let ch of seq) {
+        const to = keyMap[ch];
+        const keyPerms = buttonsToPressCoords(start, to, keyMap === keyPadMap ? { x: 0, y: 3 } : { x: 0, y: 0 });
+        allPerms.push(keyPerms);
+        start = to;
+    }
+    return allPerms.reduce((buttons, perms) => {
+        if (!buttons.length) {
+            return perms;
+        }
+        if (!perms.length) {
+            return buttons;
+        }
+        return buttons.flatMap((button) => {
+            return perms.map((perm) => button + perm);
+        });
+    }, []);
+}
+
+let sum = 0;
+
+input.split("\n").forEach((seq: string) => {
+    let buttons = buttonsForSequence(keyPadMap.A, seq, keyPadMap);
+    for (let i = 0; i < 2; i++) {
+        buttons = buttons.flatMap((seq) => {
+            return buttonsForSequence(directionMap.A, seq, directionMap);
+        });
+    }
+
+    let shortestLength: number = buttons[0].length;
+    let shortest = buttons[0];
+    buttons.forEach((perm) => {
+        if (perm.length < shortestLength) {
+            shortestLength = perm.length;
+            shortest = perm;
+        }
+    })
+
+    const seqNum = parseInt(seq.substring(-1));
+    console.log(seq);
+    console.log(shortest);
+    console.log(seqNum, shortestLength);
+    sum += (seqNum * shortestLength);
+});
+
+console.log(sum);