hatebin

const fs = require('node:fs')

let
	rucksacks = fs.readFileSync('input.txt').toString().split('\n'),
	priority = 0

//	A function that returns the priority of an item
const getPriority = (letter) => {
	let characterCodeIndex

//	Check letter case:
	if (letter.toLowerCase() === letter) {
		//	Letter is lowercase
		characterCodeIndex = 96
	}
	else {
		//	Assume letter is uppercase
		characterCodeIndex = 38
	}

//	Return converted letter to number (priority)
	return letter.charCodeAt(0) - characterCodeIndex
}

rucksacks.forEach(rucksack => {
	//	Split the rucksacks' compartments and store them as an array of items
	let
		firstCompartment	= rucksack.slice(0, rucksack.length/2).split(''),
		secondCompartment	= rucksack.slice(rucksack.length/2).split(''),
		matched = false

//	Inefficiently loop through both of the compartments:
	firstCompartment.forEach(firstItem => {
		//	If an item matched:
		if (matched === true) {
			//	Break out of the forEach loop
			return false
		}

secondCompartment.forEach(secondItem => {
			//	If an item matched:
			if (matched === true) {
				//	Break out of the forEach loop
				return false
			}
			//	If items match:
			else if (firstItem === secondItem) {
				matched = true

//	Add the priority for matched item
				priority += getPriority(firstItem)
			}
		})
	})
})

console.log(priority)