Key-Interval A*: A Faster Grid Pathfinding Algorithm

A new optimal pathfinding algorithm named Key-Interval A* (KIA*) has been introduced for 4-connected grids by researchers. Unlike current techniques that either maintain detailed search states or involve extensive preprocessing, KIA* employs a lightweight preprocessing method to create a compact abstraction of free space at the interval level. It defines free space as maximal contiguous runs of traversable cells (intervals), identifies key intervals that highlight structural boundary changes, and links them via non-key regions. The algorithm conducts an A*-style search on the key-interval graph and reconstructs grid paths from interval chains without needing cell-level local searches. The authors demonstrate KIA*'s completeness and optimality for 4-connected grids. Testing against standard benchmarks indicates that KIA* maintains exact shortest-path lengths and achieves the quickest runtime in seven out of eight benchmarks. The paper can be found on arXiv with the identifier 2607.23393.