part1.ts

import * as fs from 'fs';

const input = fs.readFileSync('input', 'utf8').split('\n');

let start = { x: 0, y: 0, e: 0 };
let end = { x: 0, y: 0, e: 0 };

const maze = input.map((line, row) =>
	line.split('').map((cell, column) => {
		if (cell === 'S') {
			return (start = { x: column, y: row, e: 'a'.charCodeAt(0) });
		} else if (cell === 'E') {
			return (end = { x: column, y: row, e: 'z'.charCodeAt(0) });
		} else {
			return { x: column, y: row, e: cell.charCodeAt(0) };
		}
	}),
);
const queue = [{ ...start, steps: 0 }];
const visited = new Set(`${start.x},${start.y}}`);

let result = 0;

while (queue.length > 0) {
	const current = queue.shift();
	if (current.x === end.x && current.y === end.y) {
		result = current.steps;
		break;
	}
	const neighbors = [
		maze[current.y - 1] && maze[current.y - 1][current.x],
		maze[current.y + 1] && maze[current.y + 1][current.x],
		maze[current.y][current.x - 1],
		maze[current.y][current.x + 1],
	]
		.filter((cell) => cell && !visited.has(`${cell.x},${cell.y}`))
		.filter((cell) => cell.e - current.e <= 1)
		.map((cell) => ({ ...cell, steps: current.steps + 1 }));
	neighbors.forEach((cell) => visited.add(`${cell.x},${cell.y}`));
	queue.push(...neighbors);
}

console.log(result);