https://hellohasan.com/2016/10/20/%e0%a6%ac%e0%a6%be%e0%a6%87%e0%a6%a8%e0%a6%be%e0%a6%b0%e0%a6%bf-%e0%a6%b8%e0%a6%be%e0%a6%b0%e0%a7%8d%e0%a6%9a-binary-search-algorithm/