select kth element

(classic problem)

Definition: Find the kth smallest element of a set. Two approaches are a modified distribution sort or select and partition.

Also known as selection problem, find kth least element, kth smallest element.

See also Select, MODIFIND, Find, reservoir sampling.

Note: The select-and-partition approximately divides in half the number of elements that must be considered at each step. The modified distribution sort divides by m the number of elements at each step. The latter is faster, but the former is more generally applicable.

Author: PEB

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Entry modified 14 January 2009.
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Cite this as:
Paul E. Black, "select kth element", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 14 January 2009. (accessed TODAY) Available from: