AdventOfCode-ts-2023/9/9_common.ts

import { ExtractNumbers } from "../common.ts";

/**
 * Parse the input for day 9
 *
 * @param inputArr An array of strings containing numbers
 * @returns An array of histograms
 */
export function ParseInput(inputArr: string[]): Histogram[] {
    return inputArr.map((historyStr) => ExtractNumbers(historyStr) as Histogram);
}

/**
 * Find the difference of values in a histogram
 *
 * @param histogram A array of historical values, or another differential
 * @returns A new histogram containing the difference of values in the input histogram
 */
export function FindDifferential(histogram: Histogram): Histogram {
    const differential: Histogram = [];

    for (let i = 1; i < histogram.length; i++) {
        differential.push(histogram[i] - histogram[i - 1]);
    }

    return differential;
}

/** An array of historical environment values */
export type Histogram = number[];