/**

* Running time = O(log n)

* Ω(1) in best case

* Binary Search in a array of numbers ordered

* @param {number} search number in array

* @param {Array} array of numbers ordered

* @returns {number} index in array where number was found

*/

function binarySearch(search, arr) {

let low = 0

let high = arr.length - 1

while (low <= high) {

let middle = Math.floor((low + high) / 2)

let guess = arr[middle]

if (guess === search) {

return middle

} else if (guess < search) {

low = middle + 1

} else {

high = middle - 1

}

}

return -1

}

const arr = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13];

const index = binarySearch(13, arr);

if (index != -1) {

console.log(`Number found at index %d`, index)

} else {

console.log(`Number not found at index`)

}