Go Binary Search

binary_search.go

package main

import (
	"log"
)

func main() {
	assert(false, binarySearch([]int{}, 5))
	assert(false, binarySearch([]int{4}, 5))
	assert(true, binarySearch([]int{5}, 5))
	assert(true, binarySearch([]int{1, 2, 3, 4, 5}, 5))
	assert(true, binarySearch([]int{1, 2, 3, 4, 5}, 1))
	assert(true, binarySearch([]int{1, 2, 3, 4, 5}, 3))
	assert(true, binarySearch([]int{1, 2, 3, 4, 5, 6, 7, 8, 9}, 8))
	assert(false, binarySearch([]int{1, 2, 3, 4, 5, 6, 7, 8, 9}, 10))
}

func binarySearch(arr []int, n int) bool {
	if len(arr) == 0 {
		return false
	}

	midIndex := len(arr) / 2
	if arr[midIndex] == n {
		return true
	}

	if arr[midIndex] < n {
		return binarySearch(arr[midIndex+1:], n)
	}

	return binarySearch(arr[:midIndex], n)
}

func assert(expected, actual interface{}) {
	if expected != actual {
		log.Panicf("%s != %s", expected, actual)
	}
}