binarySearchRecursive-steps.js

// O(log n) - logarithmic

let steps = 0
function binarySearchRecursive(n, target, start, end) {
  steps++

  if (start > end) return -1

  let middle = Math.floor((start + end) / 2)

  if (n[middle] === target) return `index ${middle} steps ${steps}`
  else if (n[middle] < target)
    return binarySearchRecursive(n, target, middle + 1, end)
  else if (n[middle] > target)
    return binarySearchRecursive(n, target, start, middle - 1)
}

let n = [
  1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
  23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
  42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60,
  61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
  80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98,
  99, 100,
]
let target = 1
let start = 0
let end = n.length - 1

console.log(binarySearchRecursive(n, target, start, end))
console.log(binarySearchRecursive(n, 50, start, end))
console.log(binarySearchRecursive(n, 62, start, end))
console.log(binarySearchRecursive(n, 100, start, end))