Count-min sketch

Count-min sketch is a probabilistic data structure that’s used to estimate the frequency of elements in a data stream. It provides an approximate representation of the frequency distribution of elements while using a small amount of memory. Count-min sketch is particularly useful in scenarios where memory is limited or when processing large-scale data streams in real time.

Count-min sketch consists of a two-dimensional array of counters, with the number of rows and columns determined by the desired accuracy and error rate. When an element is encountered in the data stream, multiple hash functions are applied to determine the positions in the array to increment the corresponding counters. By using multiple hash functions, collisions are distributed, and the frequency of elements is estimated across different counters.

Let’s consider an example to understand this better. We have a stream of four alphabets (A, B, C, and D) coming to our system and...