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The above is an approximation. The exact worst-case number of comparisons during the heap-construction phase of heapsort is known to be equal to 2n − 2s 2 (n) − e 2 (n), where s 2 (n) is the number of 1 bits in the binary representation of n and e 2 (n) is the number of trailing 0 bits. [6] [7]
But given a worst-case input, its performance degrades to O(n 2). Also, when implemented with the "shortest first" policy, the worst-case space complexity is instead bounded by O(log(n)). Heapsort has O(n) time when all elements are the same. Heapify takes O(n) time and then removing elements from the heap is O(1) time for each of the n elements.
Cuckoo hashing is a form of open addressing collision resolution technique which guarantees () worst-case lookup complexity and constant amortized time for insertions. The collision is resolved through maintaining two hash tables, each having its own hashing function, and collided slot gets replaced with the given item, and the preoccupied ...
A skip list does not provide the same absolute worst-case performance guarantees as more traditional balanced tree data structures, because it is always possible (though with very low probability [5]) that the coin-flips used to build the skip list will produce a badly balanced structure. However, they work well in practice, and the randomized ...
One implementation can be described as arranging the data sequence in a two-dimensional array and then sorting the columns of the array using insertion sort. The worst-case time complexity of Shellsort is an open problem and depends on the gap sequence used, with known complexities ranging from O(n 2) to O(n 4/3) and Θ(n log 2 n).
The number of operations required depends only on the number of levels the new element must rise to satisfy the heap property. Thus, the insertion operation has a worst-case time complexity of O(log n). For a random heap, and for repeated insertions, the insertion operation has an average-case complexity of O(1). [4] [5]
In computer science, a strict Fibonacci heap is a priority queue data structure with low worst case time bounds. It matches the amortized time bounds of the Fibonacci heap in the worst case. To achieve these time bounds, strict Fibonacci heaps maintain several invariants by performing restoring transformations after every operation.
Weak heaps may be used to sort an array, in essentially the same way as a conventional heapsort. [3] First, a weak heap is built out of all of the elements of the array, and then the root is repeatedly exchanged with the last element, which is sifted down to its proper place. A weak heap of n elements can be formed in n − 1 merges. It can be ...