aoc-2021/day03/day03.ts

import { filter, isOutOfBound, map, mapWithIndex, reduce } from "fp-ts/lib/Array";
import { pipe } from "fp-ts/lib/function";
import { startsWith } from "fp-ts/lib/string";

import { diagnostics } from "./input";
import { diagnostics as testDiagnostics } from "./input.test";

type Stat = { ones: number, zeros: number };

const bitStats = (as: string[]): Stat[] => pipe(
  as,
  reduce(
    [] as Stat[],
    (acc, bits) => pipe(
      [...bits],
      mapWithIndex((i, b) => ({
        ones: b === "1" ? (acc[i]?.ones ?? 0) + 1 : (acc[i]?.ones ?? 0),
        zeros: b=== "0" ? (acc[i]?.zeros ?? 0) + 1 : (acc[i]?.zeros ?? 0)
      }))
    )
  )
);
const mostCommonBits = (as: Stat[]) => pipe(
  as,
  map(({ ones, zeros }) => ones < zeros ? "0" : "1")
);
const leastCommonBits = (as: Stat[]) =>  pipe(
  as,
  map(({ ones, zeros }) => ones < zeros ? "1" : "0")
);


const diagBitStats = pipe(
  diagnostics,
  bitStats
);
const gamma = pipe(diagBitStats, mostCommonBits).join("");
const epsilon = pipe(diagBitStats, leastCommonBits).join("");


console.log("gamma rate is  ", gamma);
console.log("epsilon rate is", epsilon);
console.log("power consumption is", parseInt(gamma, 2) * parseInt(epsilon, 2));





const calculator = (evaluate: typeof mostCommonBits) => (diagNumbers: string[]) => {
  const iterator = (as: string[], currFilter: string): string => {
    const filteredDiagNumbers = pipe(as, filter(startsWith(currFilter)));
    if (isOutOfBound(1, filteredDiagNumbers)) {
      return filteredDiagNumbers[0];
    }
    const newFilterChar = pipe(filteredDiagNumbers, bitStats, evaluate)[currFilter.length];
    return iterator(filteredDiagNumbers, currFilter + newFilterChar);
  }
  return iterator(diagNumbers, "");
};
const oxygenRatingCalculator = calculator(mostCommonBits);
const co2RatingCalculator = calculator(leastCommonBits);



const oxygenRating = pipe(diagnostics, oxygenRatingCalculator);
const co2Rating = pipe(diagnostics, co2RatingCalculator);

console.log("oxygen generator rating is", oxygenRating);
console.log("CO2 scrubber rating is", co2Rating);
console.log("life support rating is", parseInt(oxygenRating, 2) * parseInt(co2Rating, 2));