Problem 1056. Partial sorting algorithm

Created by Paul Peeling

Solve Later

Return the top k elements of an input vector. A comparison function compareFcn(m,n) is provided to compare individual elements of the vector. The function returns true is element m should be ranked higher than element n. e.g.

partial_sort([4 3 2 1], 2, @(m,n) m > n)

ans =

       4     3

partial_sort([4 3 2 1], 2, @(m,n) m < n)

ans =

       1     2

All elements in the input vector will be unique.

Solutions will be ranked on the total number of times comparison functions are called, over all the test cases.

Solve

Solution Stats

36 Solutions
9 Solvers

Last Solution submitted on Aug 03, 2022

Last 200 Solutions

Problem Comments

4 Comments

4 Comments

Show 1 older comment

Christopher on 26 Nov 2012

Argh! The 'mod sorting' has me flummoxed!

Christian Schröder on 20 May 2023

Is this broken? On my machine at least the anonymous comparison function is not found in profile('info').

Christian Schröder on 20 May 2023

Also, note that in the "mod comparison" case, the ordering has some unintuitive properties. For instance, 30 > 6 since 30 divides 6 and 30 ~ 20 since neither divides the other, but 20 ~ 6 for the same reason, meaning that ~ is not transitive using this comparison function.

Christian Schröder on 20 May 2023

A final issue: the comparison the "mod comparison" case does not match the description in the problem. The problem states that this function should return "true [if] element m should be ranked higher than element n" (m > n), but in this test case, the function also returns true when m is equal to n (and so implements m >= n).

Solution Comments

Show comments

Problem Recent Solvers9

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 1056. Partial sorting algorithm

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers9

Suggested Problems

More from this Author5

Problem Tags

Community Treasure Hunt

Problem 1056. Partial sorting algorithm

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers9

Suggested Problems

More from this Author5

Problem Tags

Community Treasure Hunt

Players