# Heavy Hitters ### Overview > Find the elements that occur most frequently in a list. For example: > `apple, banana, apple, apple, apple, orange, pear, apple, apple` > Here the element that occurs most frequently is apple. Visually, if we did a value counts of the list, we want to find the elements that make up the majority of the mass. This problem is solved via [Count-min Sketch](Count-min%20Sketch.md). ### Background We start with an array $A$ of length $n$, and also a parameter $k$. We should think of $n$ as very large (in the hundreds of millions or billions), and $k$ as modest (10, 100, or 1000). The goal is to compute the values that occur in the array at least $\frac{n}{k}$ times. Note that there can be at most $k$ such values, and there may in fact be none.  --- Date: 20210628 Links to: [Computer Science MOC](Computer%20Science%20MOC.md) [Algorithms and Data Structures](Algorithms%20and%20Data%20Structures.md) [Count-min Sketch](Count-min%20Sketch.md) Tags: #review References: * [Heavy Hitters video](https://www.youtube.com/watch?v=5vl8n_NxpV8) * [Tim roughgarden, pdf](http://timroughgarden.org/s17/l/l2.pdf)