Last week, I wrote about the benefits of carefully studying even simple algorithms like binary search, which provides a fast way to find an element in a sorted array. Once you understand how that algorithm works, you can adapt it to solve other problems. For example:

Given an array of integers and an integer L, find the position of the first element of the array that is greater than or equal to L.

The standard binary search algorithm looks for an exact match. If the target key is not in the array, the search fails (returns a “not found” value). So if we want to handle an inequality, we’ll have to make a few changes. Here are the key points of the revised algorithm.