Algorithms and Data Structures

Volume 3608 of the series Lecture Notes in Computer Science pp 49-60

The Complexity of Implicit and Space Efficient Priority Queues

  • Christian W. MortensenAffiliated withIT University of Copenhagen
  • , Seth PettieAffiliated withMax Planck Institut für Informatik

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In this paper we study the time-space complexity of implicit priority queues supporting the decreasekey operation. Our first result is that by using one extra word of storage it is possible to match the performance of Fibonacci heaps: constant amortized time for insert and decreasekey and logarithmic time for deletemin. Our second result is a lower bound showing that that one extra word really is necessary. We reduce the decreasekey operation to a cell-probe type game called the Usher’s Problem, where one must maintain a simple data structure without the aid of any auxiliary storage.