Problem context and objectives
Mission briefing
Portal network mechanic · Travel portals are connected as a one-way chain
Repair the links without losing the unexplored route: The Partition Sentinels.
Overwrite one next pointer too early and the rest of the expedition becomes unreachable.
How you win
- 1Recognize when Dual dummy lists matches the clues
- 2Keep this true after every move: both partial chains preserve the original relative order of their group
- 3Reach the result within O(n)
Rules and pressure
- Target cost: O(n)
- State rule: both partial chains preserve the original relative order of their group
New words in this mission
Open a term for a plain-language explanation.partition or shard+
One slice of a larger dataset or workload. Splitting work raises capacity, but cross-slice operations become harder.
Lesson 1 of 3
Every node enters exactly one rail. Watch the original index plates: order never changes inside either rail.
Your call · With pivot 3, where does value 3 go?