Example 1 · missing
| Call | Returns |
|---|---|
NewExpiringStore() | Instance 1 |
instance1.Get("x", 0) | Missing (found = false) |
instance1.Delete("x", 0) | false |
Test data
- Input
{"ops":[["get","x",0],["delete","x",0]]}- Expected output
[null,false]
Expiring key-value store
Expiring key-value store
MediumYour task
- Build an in-memory key-value store with set, get and delete.
- A write stores or replaces the value for a key.
- A get returns its value or an explicit missing result.
- A delete returns whether a key was present and removes it when present.
- Empty strings are valid values.
- Keep separate stores independent.
Required API
- NewExpiringStore
func NewExpiringStore() *ExpiringStore - ExpiringStore.Set
func (s *ExpiringStore) Set(key, value string, ttl, now int64) - ExpiringStore.Get
func (s *ExpiringStore) Get(key string, now int64) (string, bool) - ExpiringStore.Delete
func (s *ExpiringStore) Delete(key string, now int64) bool
Constraints
- For this part, every operation occurs before the stored value expires.
- Keep the provided ttl and now arguments in your interface; expiry behavior will be introduced in the next part.
- Keys are valid case-sensitive ASCII identifiers, 1–32 characters.
- Values are ASCII strings, 0–64 characters.
- At most 1,000 operations occur per store.
- Use only the standard library.
Examples
The runner calls your functions directly; you do not need to parse JSON.
Example 2 · empty and delete
| Call | Returns |
|---|---|
NewExpiringStore() | Instance 1 |
instance1.Set("x", "", 10, 0) | No return value |
instance1.Get("x", 0) | "" |
instance1.Delete("x", 1) | true |
instance1.Get("x", 1) | Missing (found = false) |
instance1.Delete("x", 1) | false |
Test data
- Input
{"ops":[["set","x","",10,0],["get","x",0],["delete","x",1],["get","x",1],["delete","x",1]]}- Expected output
[null,"",true,null,false]
Related guides
Part 1 only.
Solution guide
Reveal solution guide — spoilers
Approach
- Store each key and its current value in a map owned by this instance.
- Replace an existing entry on a write. Distinguish a missing key from an empty stored string.
Why it works
The map contains exactly the latest value for each present key, so lookups and replacements agree.
Complexity
Expected O(1) lookup and write with bounded key length, using O(k) storage for k entries.
Edge cases to check
- Check missing and case-sensitive keys, empty values, replacement, and independent instances.
Restoring local drafts…
Checking execution availability…
Public examples
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