src/gcd.js

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Ladder Summary

file Provides a `gcd` function that computes the greatest common divisor of two integers using the Euclidean algorithm, handling non‑numeric inputs by returning undefined, normalizing inputs to absolute truncated integers, and correctly returning 0 when both inputs are zero.

/**
 * Computes the greatest common divisor (GCD) of two integers using the Euclidean algorithm.
 *
 * @param {number} a - First integer.
 * @param {number} b - Second integer.
 * @returns {number} The GCD of a and b. Returns 0 if both inputs are 0.
 */
export function gcd(a, b) {
  // Ensure inputs are numbers; if not, return undefined (consistent with other utilities)
  if (typeof a !== "number" || typeof b !== "number") return undefined;
  // Work with absolute integer values
  a = Math.abs(Math.trunc(a));
  b = Math.abs(Math.trunc(b));

  // Euclidean algorithm
  while (b !== 0) {
    const temp = b;
    b = a % b;
    a = temp;
  }
  return a;
}