Cad is foclóir/léarscáil ann agus conas a bhíonn sé difriúil ó thacar?

Question

Accepted Answer

Stóraíonn **foclóir** (léarscáil, eagar comhghaolmhar) comhlachais **eochair → luach**, ag ligint duit luach a chuardach de réir a eochrach in **O(1) ar an meán**. Is **tacar** go bunúsach léarscáil le heochracha ach gan luachanna — ní stóraíonn sé ach ballraitheas.

## Example

```python
# Counting word frequencies — a classic map use
text = "the cat the dog the".split()
counts = {}
for word in text:
    counts[word] = counts.get(word, 0) + 1
# counts -> {'the': 3, 'cat': 1, 'dog': 1}

ages = {'alice': 30, 'bob': 25}
ages['alice']          # O(1) lookup by key -> 30
ages['carol'] = 40     # O(1) insert
'bob' in ages          # O(1) key membership
```

## Set vs map

| | Set | Map / Dict |
|---|---|---|
| Stores | unique keys | key → value pairs |
| Lookup | "is key present?" | "what value for key?" |
| Use | membership, dedup | associations, counting |

| Operation | Average |
|---|---|
| insert / update | O(1) |
| lookup | O(1) |
| delete | O(1) |

## Cén fáth a bhíonn sé tábhachtach

Is iad na léarscáileanna an uirlis laethúil chun sonraí a innéacsú de réir aitheantóir — taisce, cumraíocht, comhaireamh minicíochta agus grúpáil.

Cumhdaíonn foclóirí nua-aimseartha (m.sh. Python 3.7+) ord cuir isteach freisin, ag comhcheangal rochtain thapa le foluain inathraitheach.

	Set	Map / Dict
Stores	unique keys	key → value pairs
Lookup	"is key present?"	"what value for key?"
Use	membership, dedup	associations, counting