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# [Haskell](https://www.haskell.org) + [hgl](https://gitlab.com/wheatwizard/haskell-golfing-library), 10 bytes

```haskell
mpn$ce~<gj
````

[Attempt This Online!](https://ato.pxeger.com/run?1=m708I7E4OzUnZ8FNxczcgvyiEoXC0sSczLTM1BSFgKLUnNKUVC6oRMDS0pI0XYs1aba5BXkqyal1NulZEKGbrrmJmXkKtgop-VwKBUUKKgppCtGGOoY6RmBoCIbGOsaxCFljHXMdUx0THUugvDEQm-mYxUIMW7AAQgMA)

## Explanation

- `mpn` map across all non-empty prefixes of the input ...
- `ce` count the number of elements in each prefix equal to ...
- `gj` the last element of that prefix.

## Reflection

I'm happy with this.  It doesn't take any extra steps, and the glue is cheap.