DESERT OASIS
Oasis Cache Caravan
The caravan repeats the same long scouting trips! Build a memory cache so saved oasis maps can answer the next request instantly.
🧠 Before we start
At the Lava Trail, your program remembered choices so it could go back. Today it will remember answers. A cache saves a useful result and reuses it when the same request returns.
🔎 Check→🐪 Fetch if missing→🗄️ Save→⚡ Reuse
Challenge 1 of 4Build the cache recipe
1
Arrange the cache recipe
Tap four visual instruction blocks in the order a cache program uses them.
MY VISUAL CACHE PROGRAM
1 · CHECK
2 · REUSE?
3 · FETCH?
4 · SAVE
What should the caravan check before taking a long trip?
2
Serve four map requests
Check the cache first. On a miss, scout and save. On a hit, use the saved map—no extra trip!
NEXT MAP REQUEST🌴 PALM WELL
📭PALM WELL
empty
empty
📭MOON RUINS
empty
empty
Requests: 0 / 4 · Long trips: 0 · Cache hits: 0
Start every request by checking the cache.
3
Refresh a stale map
A sandstorm moved the Palm Well marker. Old saved answers can become stale. Choose the safe cache action.
⚠️ PALM WELL CACHEOld path · before sandstorm
The cache is fast only when its saved answer is still trustworthy.
4
Debug the mixed-up key
Both maps were saved under one vague key. Pick a repair so each request finds its own answer.
KEY: WATER🌴 Palm Well map
KEY: WATER🌙 Moon Ruins map
Why can one WATER key not choose between two different maps?
🌟 What you learned
- A cache stores answers that may be needed again.
- Programs check the cache before doing slow work.
- A cache miss means fetch the answer, then save it.
- A cache hit reuses a saved answer and avoids repeated work.
- Stale answers need refreshing, and unique keys stop mix-ups.