1) Database index technique
Found on
https://www.crosswordclues.com/clue/quadtree
A quadtree is a tree data structure in which each internal node has exactly four children. Quadtrees are most often used to partition a two-dimensional space by recursively subdividing it into four quadrants or regions. The regions may be square or rectangular, or may have arbitrary shapes. This data structure was named a quadtree by Raphael Finke...
Found on
http://en.wikipedia.org/wiki/Quadtree
No exact match found.
