day11_1.js

const { parse } = require('path');
const path = require('path');
const fs = require('fs');

const lineReader = require('readline').createInterface({
  input: fs.createReadStream('input.txt'),
});

const data = [];
let galaxies = [];
let row = 0;
let paths = [];

function getGalaxyAtPosition(row, col) {
  let galaxyIndex = 0;
  galaxies.forEach((galaxy, index) => {
    if (galaxy[0] === row && galaxy[1] === col) {
      galaxyIndex = index;
      return;
    }
  });
  return galaxyIndex;
}

function dfs(galaxy) {
  const visited = Array.from({ length: data.length }, () =>
    Array(data[0].length).fill(false)
  );
  const queue = [[galaxy[0], galaxy[1], 0]];
  const pathLengths = Array(galaxies.length).fill(0);
  while (queue.length !== 0) {
    const point = queue.shift();
    const row = point[0];
    const col = point[1];
    const length = point[2];
    if (
      row < 0 ||
      row >= data.length ||
      col < 0 ||
      col >= data[0].length ||
      visited[row][col]
    ) {
      continue;
    }
    if (data[row][col] === '#') {
      const index = getGalaxyAtPosition(row, col);
      pathLengths[index] = length;
    }
    visited[row][col] = true;
    queue.push([row + 1, col, length + 1]);
    queue.push([row - 1, col, length + 1]);
    queue.push([row, col + 1, length + 1]);
    queue.push([row, col - 1, length + 1]);
  }
  paths.push(pathLengths);
}

lineReader.on('line', function (line) {
  data.push(line);
  const y = line.indexOf('#');
  if (y === -1) {
    data.push(line);
  }
  row++;
});

lineReader.on('close', function () {
  let j = 0;
  while (j < data[0].length) {
    const column = [];
    for (let i = 0; i < data.length; i++) {
      column.push(data[i][j]);
    }
    if (column.includes('#')) {
      j++;
      continue;
    }
    for (let i = 0; i < data.length; i++) {
      const newRow = [...data[i]];
      newRow.splice(j, 0, '.');
      data[i] = newRow;
    }
    j += 2;
  }

  galaxies = [];
  for (let i = 0; i < data.length; i++) {
    for (let j = 0; j < data[0].length; j++) {
      if (data[i][j] === '#') {
        galaxies.push([i, j]);
      }
    }
  }
  galaxies.forEach((galaxy) => {
    dfs(galaxy);
  });
  let sum = 0;
  for (let i = 0; i < paths.length; i++) {
    for (let j = i + 1; j < paths[0].length; j++) {
      sum += paths[i][j];
    }
  }
  console.log(sum);
});