Sorting algorithms statistics

Algorithm Worst-case running time Average-case/expected running time
Insertion sort Θ(n2) Θ(n2)
Merge sort Θ(n lgn) Θ(n lgn)
Heapsort O(n lgn) -
Quicksort Θ(n2) Θ(n lgn) (expected)
Counting sort Θ(k + n) Θ(k + n)
Radix sort Θ(d (n + k)) Θ(d (n + k))
Bucket sort Θ(n2) Θ(n) (average-case)

O - assymptotic upper bound.
Θ - assymptotically tight bounds.