Bounded LRU cache

Your task

Build a small in-memory cache with get and put.
A put stores or replaces the value for a key.
A get returns its current value or an explicit missing result.
Empty strings are valid values.
Separate caches must not share state.

Required API

NewCache
func NewCache(capacity int) *Cache
Cache.Get
func (c *Cache) Get(key string) (string, bool)
Cache.Put
func (c *Cache) Put(key, value string)

Behavior

In this part capacity is positive and the number of distinct keys never exceeds it.
Keep the capacity constructor argument.
Eviction and recency behavior come in the next part.
Keys are valid case-sensitive ASCII identifiers, 1–32 characters.
Values are ASCII strings, 0–64 characters.
There are at most 1,000 operations per cache.
Use only the standard library.

Notes and example notation

Examples specify capacity and operations ["put", key, value] or ["get", key].
Each output position corresponds to one operation; put produces null.

Examples

The runner calls your functions directly; you do not need to parse JSON.

Example 1 · missing

Calls in order; values are shown as data.
Call	Returns
`NewCache(2)`	Instance 1
`instance1.Get("x")`	Missing (found = false)

Test data

Input

{"capacity":2,"ops":[["get","x"]]}

Expected output

[null]

Example 2 · store and overwrite

Calls in order; values are shown as data.
Call	Returns
`NewCache(2)`	Instance 1
`instance1.Put("A", "1")`	No return value
`instance1.Get("A")`	"1"
`instance1.Put("A", "2")`	No return value
`instance1.Get("A")`	"2"

Test data

Input

{"capacity":2,"ops":[["put","A","1"],["get","A"],["put","A","2"],["get","A"]]}

Expected output

[null,"1",null,"2"]

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