day 3/index.ts

import { readFileSync } from "fs";

const input = readFileSync('./input.txt').toString().split('\n');

type coord = `${number}:${number}`

const coords: Record<coord, string> = {};

const ignoreCoords: coord[] = []

function formatCoords(x: number, y: number): coord {return `${x}:${y}`}

// INPUT CURRENT COORDS
function checkNumChar(x: number, y: number, currentNum?: string): undefined | string {
   if (ignoreCoords.includes(formatCoords(x,y))) return
   currentNum = currentNum ?? ""
   const char = input[y][x];
   if(isNaN(parseInt(char))) return currentNum;
   ignoreCoords.push(formatCoords(x,y))
   currentNum += char;
   return checkNumChar(x+1, y, currentNum);
}

let i = 0;
for(const line of input) {
   let j = 0;
   for (const char of line) {
      if (char === ".") {
         j++;
         continue;
      } else if(isNaN(parseInt(char))) {
         coords[formatCoords(j,i)] = char
      } else {
         const num = checkNumChar(j,i);
         // console.log(num)
         if(num) coords[formatCoords(j,i)] = num as string
      }
      j++;
   }
   i++;
}

// Part 1
let sum = 0;
for(const [loc, val] of Object.entries(coords)) {
   if(isNaN(parseInt(val))) continue;

   // Parse Coords
   const [x,y] = loc.match(/\d+/g)!.map(s => parseInt(s)) as [number, number]

   // Check Next Door
   const lx = x-1;
   const rx = x + 1 + val.length;

   if(
      coords[formatCoords(lx,y)] ||
      coords[formatCoords(rx,y)]
   ) {
      sum += parseInt(val);
      continue;
   }
   
   // Check Above / Below w/ diagonals
   const ay = y - 1;
   const by = y + 1;

   for(let i = -1; i <= val.length; i++) {
      if(
         coords[formatCoords(x+i, ay)] ||
         coords[formatCoords(x+i, by)]
      ) {
         sum += parseInt(val)
         break;
      }
   }
}

console.log(sum);