Learn Big-O notation from zero and the time and space cost of the core data structures, searches and sorts. For coding interviews and computer science courses, from simple loops to hash maps, trees and graphs.
Big-O names the shape of growth, not a time: O(n) means the work rises in step with the input, O(n²) with its square. The curves show how differently those shapes climb once the input gets large. Strictly, Big-O states an upper bound on that growth. The O stands for Ordnung, German for order: the notation comes from Paul Bachmann (1894) and was spread by Edmund Landau.
