solution02.txt

Question #2: Array Deduping

Prompt: Write an algorithm that removes duplicates from an array. Do not use a function like filter() to solve this. Once you have solved the problem, demonstrate how it can be solved with filter(). Solve the problem with and without recursion.

Questions for interviewers:
- Will numbers always be passed as integers? (no numbers as strings?)

Possible edge cases: 
- An empty array

Example Inputs/Outputs:
Input: [7, 9, "hi", 12, "hi", 7, 53]
Output: [7, 9, "hi", 12, 53]

Input: [3, 3, 3, 3]
Output: [3]

Input: [3, "3"]
Output: [3, "3"] ? // technically, these elements are not duplicates as they are different datatypes

Input: []
Output: []


Solution without recursion or filter:
1. Copy the original array using spread syntax
2. Use the Set object to create a new array of unique elements

let array = [7, 9, "hi", 12, "hi", 7, 53];
function removeDupes(array) {
	let noDupes = [...new Set(array)]
	return noDupes;
}

// using a foreach
function removeDupes(array) {
	let noDupes = [];
	array.forEach(function(element) {
		if(!noDupes.includes(element)) {
			noDupes.push(element);
		}
	});
}	

Solution with filter:
1. Compare all elements in array to see if the index is the first time that element appears
2. Create new array with unique elements

let array = [7, 9, "hi", 12, "hi", 7, 53];
function removeDupes(array) {
	let uniqueArray = array.filter(function(element, index) {
		return array.indexOf(element) === index;
	});
	return uniqueArray;
}

Solution with recursion:
Write a function that takes an array, if that array's length is 0, break out of the recursive loop.
Create a constant array to 

const array = [7, 9, "hi", 12, "hi", 7, 53];

const removeDupes = (array) => {
	if (array.length === 0) {
		return array.concat([]);
	}
	const uniqueArray = array.slice(0, -1); // create new array based off of original
	if (uniqueArray.includes(array[array.length - 1])) { // compare the arrays
		return removeDupes(uniqueArray) // if match is found, return and call the function again
	} else {
		return removeDupes(uniqueArray).concat(array[array.length - 1]) // if no match is found, search the next index
	}
}