# API: CSHeap
Status: `Ready`
## Purpose
Count Sketch with integrated heavy-hitter heap (`HHHeap`) for top-k tracking.
## Type/Struct
- `CSHeap<S = Vector2D<i64>, M = RegularPath, H = DefaultXxHasher>`
## Constructors
```rust
fn new(rows: usize, cols: usize, top_k: usize) -> Self
fn from_storage(storage: S, top_k: usize) -> Self
fn default() -> Self
```
## Insert/Update
```rust
fn insert(&mut self, key: &DataInput)
fn insert_many(&mut self, key: &DataInput, many: S::Counter)
fn bulk_insert(&mut self, values: &[DataInput])
fn clear_heap(&mut self)
```
## Query
```rust
fn estimate(&self, key: &DataInput) -> f64
fn rows(&self) -> usize
fn cols(&self) -> usize
fn cs(&self) -> &Count<S, M, H>
fn heap(&self) -> &HHHeap
```
## Merge
```rust
fn merge(&mut self, other: &Self)
```
## Serialization
Not currently provided as a dedicated public API.
## Examples
```rust
use asap_sketchlib::{CSHeap, DataInput, Vector2D, RegularPath};
let mut sk = CSHeap::<Vector2D<i64>, RegularPath>::new(5, 256, 8);
sk.insert(&DataInput::Str("flow"));
assert!(sk.estimate(&DataInput::Str("flow")) >= 1.0);
```
## Caveats
- Estimate semantics follow Count Sketch and may be non-integer.
- Merge requires matching dimensions and compatible type parameters.
## Status
Useful helper wrapper; tested but less central than base sketches.