Danjb1 · March 9, 2020 12:27
diff --git a/WIN-sequence-challenge.js b/WIN-sequence-challenge.js
 /*
 * TASK:
 * Calculate the 15th element for this sequence: 2, 2, 4, 6, 10, 16, ...
 */

 const sequence = (n) => {
  if (n < 0) {
    throw new Error('n must be >= 0');
  }
  return _sequence(n, 0, 0, 0);
 }

 const _sequence = (n, i, prev1, prev2) => {
  const thisElem = (i <= 1)
      ? 2
      : prev1 + prev2;
  return i == n
      ? thisElem
      : _sequence(n, i + 1, prev2, thisElem);
 }

 for (let i = 0; i < 15; i++) {
  console.log(i + ' -> ' + sequence(i));
 }

 /*
 * QUESTIONS:
 *
 * 1) What is the 15th element of the sequence?
 *
 *      1220
 *
 * 2) What is your solution time and space complexity, for the n(th) element
 *    of the sequence?

 *      Time complexity = O(n)
 *      Space complexity = O(n), due to the recursive call stack
 * 
 *      This could become O(1) if a loop was used instead.
 *
 * 3) What clean code principles have been used, and why?
 *
 *      - Line breaks to enhance readability
 *      - Sensible variable names for readability
 *      - Clean public interface (sequence), with the internal implementation
 *          details kept private (_sequence), for ease of use
 */
	/*
	* TASK:
	* Calculate the 15th element for this sequence: 2, 2, 4, 6, 10, 16, ...
	*/

	const sequence = (n) => {
	if (n < 0) {
	throw new Error('n must be >= 0');
	}
	return _sequence(n, 0, 0, 0);
	}

	const _sequence = (n, i, prev1, prev2) => {
	const thisElem = (i <= 1)
	? 2
	: prev1 + prev2;
	return i == n
	? thisElem
	: _sequence(n, i + 1, prev2, thisElem);
	}

	for (let i = 0; i < 15; i++) {
	console.log(i + ' -> ' + sequence(i));
	}

	/*
	* QUESTIONS:
	*
	* 1) What is the 15th element of the sequence?
	*
	* 1220
	*
	* 2) What is your solution time and space complexity, for the n(th) element
	* of the sequence?

	* Time complexity = O(n)
	* Space complexity = O(n), due to the recursive call stack
	*
	* This could become O(1) if a loop was used instead.
	*
	* 3) What clean code principles have been used, and why?
	*
	* - Line breaks to enhance readability
	* - Sensible variable names for readability
	* - Clean public interface (sequence), with the internal implementation
	* details kept private (_sequence), for ease of use
	*/