adventofcode/2021/08/part2.mjs

import fs from "fs-extra";
import fp from "lodash/fp.js";
import _ from "lodash";

import * as p1 from './part1.mjs';

function decodedDigits(mapping) {
            const s = fp.invert(mapping);
            let solution = fp.invert(p1.digits);
            solution = fp.mapKeys(
                k => k.split('').map(
                    l => s[l]
                ).join('')
                ,solution );

            solution = fp.mapKeys( k => { k = k.split('').sort().join(''); return k }, solution );

            return solution;
}

function guess(unknowns,guessed={},inputs) {
    console.log({unknowns,guessed});

    const [ next ] = Object.keys(unknowns);

    if(!next) return guessed;


    if(unknowns[next].size === 0) return;


    for ( const p of unknowns[next].values() ) {
        let newUnknowns = fp.omit(next, unknowns);
        newUnknowns = fp.mapValues(
            s => {
                const x = new Set(s.values());
                x.delete(p);
                return x;
            }, newUnknowns );

            //console.log({ newUnknowns })
        if(
            Object.values(newUnknowns).some( s => s.size === 0 )
        ) continue;

        const r = guess( newUnknowns, { ...guessed, [next]: p }, inputs );
        if(r) {
            const s = fp.invert(r);
            let solution = fp.invert(p1.digits);
            solution = fp.mapKeys(
                k => k.split('').map(
                    l => s[l]
                ).join('')
                ,solution );

            solution = fp.mapKeys( k => { k = k.split('').sort().join(''); return k }, solution );

            console.log({r, solution });
            console.log({inputs})

            if( inputs.some( i => ! solution.hasOwnProperty(i.join(''))  ) ) {
                console.log("Oh noes");
            } else {
                console.log("Oh yea");
                return r;
            }

        }
    }
}

export function findMapping(input) {
    const values = 'abcdefg'.split('');

    const possibility = Object.fromEntries(values.map(
        v => [ v, new Set(values) ]
    ));

    for ( const seq of input ) {
        const p = Object.values(p1.digits).filter(
            d => d.length === seq.length
        ).join('').split('');

        for( const l of seq ) {
                possibility[l] = new Set(
                    p.filter( x => possibility[l].has(x) )
                );
        }
       // console.log(possibility);
    }



    const one   = input.find( i => i.length === 2 );
    const seven = input.find( i => i.length === 3 );
    const [a] = seven.filter( x => !one.includes(x) );

    for( const l of Object.values(possibility) ) {
        l.delete('a');
    }

    possibility[a] = new Set(['a']);
    console.log(possibility);

    return guess(possibility,{},input);
}

export function decodedOutput({input,output}) {
    const mapping = findMapping([...input,...output]);

    const digits = decodedDigits(mapping);

    console.log({ digits, output });

    return parseInt(output.map( e => digits[e.join('')] ).join(''));
}

export function solution(input) {

    return _.sum( input.map( decodedOutput ) );

}