What is a dynamic array and what is the complexity of insertion?

A dynamic array is a data structure that automatically adjusts its size when elements are added, typically increasing its capacity several times when the current size is full.

Inserting an element into a dynamic array usually has an amortized complexity of O(1). This means that on average, insertion occurs in constant time, although sometimes during array expansion (copying elements to a new larger array), the operation takes O(n).

Example: In Go, slices (slice) are implemented based on dynamic arrays. When adding elements using append, Go automatically increases the slice's capacity when necessary.