Interleaved Mergesort

Abstract

We present a new mergesort algorithm which is based on partitioning the input list in an interleaving manner. The new algorithm has a better performance that the classic mergesort algorithm does. On the average, the new algorithm runs in O(n log n) time using O(√n) extra space, where n is the size of the array to be sorted. In the worst case, depending on the implementation, the new algorithm may have O(n log n) running time using O(n) extra space, which is the same as the classic mergesort, or it may have O(n√n) running time using O(√n) extra space.