1346. Check If N and Its Double Exist.js

// Given an array arr of integers, check if there exist two indices i and j such that :

// i != j
// 0 <= i, j < arr.length
// arr[i] == 2 * arr[j]

// Example 1:

// Input: arr = [10,2,5,3]
// Output: true
// Explanation: For i = 0 and j = 2, arr[i] == 10 == 2 * 5 == 2 * arr[j]
// Example 2:

// Input: arr = [3,1,7,11]
// Output: false
// Explanation: There is no i and j that satisfy the conditions.

const checkIfExist = arr => {
	const set = new Set()

	for (const currValue of arr) {
		if (set.has(currValue)) {
			return true
		}
		
		set.add(currValue * 2)
		set.add(currValue / 2)
	}

	return false
}