day 3/index.ts

import { readFileSync } from "fs";

const input = readFileSync('./testdata.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}`}
function getCoords(crd: coord): {x: number, y: number} {
   const [x,y] = crd.match(/\d+/g)!.map(s => parseInt(s)) as [number, number]
   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]

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

   // Above / Below w/ diagonals
   const ay = y - 1;
   const by = y + 1;

   console.log(`${loc} (${val})`)
   if(
      (coords[formatCoords(lx,y)] && isNaN(parseInt(coords[formatCoords(lx,y)])))
   ) {
      console.log(`${loc} (${val}) next to: ${formatCoords(lx,y)} (${coords[formatCoords(lx,y)]})`);
      sum += parseInt(val);
      continue;
   } else if(
      coords[formatCoords(rx,y)] && isNaN(parseInt(coords[formatCoords(rx,y)]))
   ) {
      console.log(`${loc} (${val}) next to: ${formatCoords(rx,y)} (${coords[formatCoords(rx,y)]})`);
      sum += parseInt(val);
      continue;
   } else {
      for(let i = -1; i <= val.length; i++) {
         if(
            coords[formatCoords(x+i,ay)] && isNaN(parseInt(coords[formatCoords(x+i,ay)]))
         ) {
            console.log(`${loc} (${val}) next to: ${formatCoords(x+i,ay)} (${coords[formatCoords(x+i,ay)]})`);
            sum += parseInt(val)
            break;
         } else if (
            coords[formatCoords(x+i, by)] && isNaN(parseInt(coords[formatCoords(x+i, by)]))
         ) {
            console.log(`${loc} (${val}) next to: ${formatCoords(x+i,by)} (${coords[formatCoords(x+i,by)]})`);
            sum += parseInt(val)
            break;
         }
      }
   }
}

console.log(sum);

function getNumFromRight(x: number, y: number, curCoord?: coord): coord {
   curCoord = curCoord ?? formatCoords(x,y)
   const char = input[y][x];
   if(isNaN(parseInt(char))) return curCoord;
   curCoord = formatCoords(x,y)
   return getNumFromRight(x-1, y, curCoord);
}


// Part 2

let ratio = 0;
for(const [loc, val] of Object.entries(coords)) {
   if(val !== "*") continue;
   let curratio = 1;
   let curgears = 0;

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

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

   // Above / Below w/ diagonals
   const ay = y - 1;
   const by = y + 1;

   //left
   if(!isNaN(parseInt(input[y][lx]))) {
      if(coords[formatCoords(lx,y)]) {
         console.log(`${loc} next to: `)
         curratio *= parseInt(coords[formatCoords(lx,y)]);
         curgears++;
      } else {
         const n = getNumFromRight(lx,y)
         curratio *= n ? parseInt(coords[n]) : 1
         curgears++;
      }
   }

   //right
   if(!isNaN(parseInt(input[y][rx]))) {
      if(coords[formatCoords(rx,y)]) {
         curratio *= parseInt(coords[formatCoords(rx,y)]);
         curgears++;
      } else {
         const n = getNumFromRight(rx,y)
         curratio *= n ? parseInt(coords[n]) : 1
         curgears++;
      }
   }

   //above and below
   for(let i = -1; i <= 1; i++) {
      //above
      if(!isNaN(parseInt(input[ay][x+i]))) {
         if(coords[formatCoords(x+i,ay)]) {
            curratio *= parseInt(coords[formatCoords(x+i,ay)]);
            curgears++;
         } else {
            const n = getNumFromRight(x+i,ay)
            curratio *= n ? parseInt(coords[n]) : 1
            curgears++;
         }
      }
      //below
      if(!isNaN(parseInt(input[by][x+i]))) {
         if(coords[formatCoords(x+i,by)]) {
            curratio *= parseInt(coords[formatCoords(x+i,by)]);
            curgears++;
         } else {
            const n = getNumFromRight(x+i,by)
            curratio *= n ? parseInt(coords[n]) : 1
            curgears++;
         }
      }
   }
   if(curgears === 2) ratio += curratio
}

console.log(ratio)