This is an implementation of Mergesort using higher order functions,guards,where and recursion. However getting an error from compiler 6:26: parse error on input ‘=’ I can’t see whats wrong? or rather I don’t understand the compiler.
On a “traditional” merge sort, each pass through the data doubles the size of the sorted subsections. After the first pass, the file will be sorted into sections of length two. After the second pass, length four. Then eight, sixteen, etc. up to the size of the file. It’s necessary to keep doubling the size … Read more
On a “traditional” merge sort, each pass through the data doubles the size of the sorted subsections. After the first pass, the file will be sorted into sections of length two. After the second pass, length four. Then eight, sixteen, etc. up to the size of the file. It’s necessary to keep doubling the size … Read more
Knuth left this as an exercise (Vol 3, 5.2.5). There do exist in-place merge sorts. They must be implemented carefully. First, naive in-place merge such as described here isn’t the right solution. It downgrades the performance to O(N2). The idea is to sort part of the array while using the rest as working area for merging. For example … Read more
a) Yes – in a perfect world you’d have to do log n merges of size n, n/2, n/4 … (or better said 1, 2, 3 … n/4, n/2, n – they can’t be parallelized), which gives O(n). It still is O(n log n). In not-so-perfect-world you don’t have infinite number of processors and context-switching … Read more
Let’s see if we can work this out! In merge sort, at each level of the recursion, we do the following: Split the array in half. Recursively sort each half. Use the merge algorithm to combine the two halves together. So how many comparisons are done at each step? Well, the divide step doesn’t make … Read more