Advent Of Code 2017 - Day 6

Challenge-1.js

// input => [10, 3, 15, ...];
function memoryBanks(input) {
	const states = [];
	let opCount = 0;
	for (; !states.includes(input.join('|')) ;) {
		states.push(input.join('|'));
		const highestNum = Math.max.apply(null, input);
		let idx = input.indexOf(highestNum);
		let amt = input[idx];
		input[idx] = 0;
		for (idx++; amt--; idx++) {
			const wrappedIdx = (idx + input.length) % input.length;
			input[wrappedIdx]++;
		}
		opCount++;
	}
	return opCount;
}

Challenge-2.js

// input => [10, 3, 15, ...];
function memoryBanksLoopLength(input) {
	const states = [];
	let opCount = 0;
	for (; !states.includes(input.join('|')) ;) {
		states.push(input.join('|'));
		const highestNum = Math.max.apply(null, input);
		let idx = input.indexOf(highestNum);
		let amt = input[idx];
		input[idx] = 0;
		for (idx++; amt--; idx++) {
			const wrappedIdx = (idx + input.length) % input.length;
			input[wrappedIdx]++;
		}
		opCount++;
	}
	return opCount - states.indexOf(input.join('|'));
}