Randomized multidimensional search trees: lazy balancing and dynamic shuffling

Abstract

A randomized technique, called dynamic shuffling, is given for multidimensional dynamic search. This technique, when specialized to the problem of searching in sorted lists, yields the previously known randomized binary trees (treaps). The crux of the technique is a multidimensional generalization of the rotation operation on binary search trees. Simultaneously, it is shown how to dynamize the randomized incremental algorithms so as to allow additions as well as deletions of objects. The techniques are based on remembering the history of the actual or imaginary sequence of updates. The techniques are applied to several problems in computational geometry.<>