This function returns the state space of a context tree.

## Arguments

- ct
a context tree.

## Value

the state space of the context tree.

## Examples

```
dts <- c(0, 1, 1, 1, 0, 0, 1, 0, 1, 0)
dts_ctree <- ctx_tree(dts, min_size = 1, max_depth = 2)
## should be c(0, 1)
states(dts_ctree)
#> [1] 0 1
```