Day 2: Red-Nosed Reports

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FAQ

  • @sjmulder
    link
    29 days ago

    JavaScript

    Also wrote a solution in JavaScript to play around with list comprehension. Wrote some utility functions for expressiveness (and lazy evaluation).

    Code
    const fs = require("fs");
    const U = require("./util");
    
    const isSafe = xs =>
        U.pairwise(xs).every(([a,b]) => a!==b && a-b > -4 && a-b < 4) &&
        new Set(U.pairwise(xs).map(([a,b]) => a < b)).size === 1;
    
    const rows = fs
        .readFileSync(process.argv[2] || process.stdin.fd, "utf8")
        .split("\n")
        .filter(x => x != "")
        .map(x => x.split(/ +/).map(Number));
    
    const p1 = U.countBy(rows, isSafe);
    const p2 = U.countBy(rows, row =>
        isSafe(row) || U.someBy(U.indices(row),
            i => isSafe([...row.slice(0, i), ...row.slice(i+1)])));
    
    console.log("02:", p1, p2);
    

    https://github.com/sjmulder/aoc/blob/master/2024/js/day02.js