#insertion-sort

Insertion Sort

Introduction Insertion Sort builds a sorted array one element at a time by picking each element and inserting it into its correct position among the already-sorted elements. It’s exactly how most people sort a hand of playing cards — you pick up one card at a time and slide it into the right spot. Despite being O(n²) in the worst case, Insertion Sort is genuinely useful. It’s the fastest algorithm for small arrays and nearly-sorted data, which is why many standard library sort implementations (like TimSort) use it as a building block. Read more →

March 31, 2026