Binary search Swift

binary-search.swift

/**
 Returns index of item if found. Otherwise returns -1 * position where the item should be insertd to
 */
func binarySearch(arr: [Int], start: Int, end: Int, k: Int) -> Int {
    var start = start
    var end = end
    var mid = 0
    while start <= end {
        mid = start + (end - start) / 2
        if arr[mid] == k {
            return mid
        }
        if arr[mid] < k {
            // right side
            start = mid + 1
        } else {
            end = mid - 1
        }
    }
    return  -1 * start
}