
Sorting Algorithm

This is a sorting algorithm.   It may be applied to a set of data in order to sort it.    
For comparing various sorts, see compare sorts.  
For other sorting algorithms,   see sorting algorithms,   or:

O(n logn) sorts
Heap sort |
Merge sort |
Patience sort |
Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort


Use the quickselect algorithm on the vector

 [9, 8, 7, 6, 5, 0, 1, 2, 3, 4]
To show the first, second, third, ... up to the tenth largest member of the vector, in order, here on this page.

 Note: Quicksort has a separate task. 


package main
 
import "fmt"
 
func quickselect(list []int, k int) int {
    for {
        // partition
        px := len(list) / 2
        pv := list[px]
        last := len(list) - 1
        list[px], list[last] = list[last], list[px]
        i := 0
        for j := 0; j < last; j++ {
            if list[j] < pv {
                list[i], list[j] = list[j], list[i]
                i++
            }
        }
        // select
        if i == k {
            return pv
        }
        if k < i {
            list = list[:i]
        } else {
            list[i], list[last] = list[last], list[i]
            list = list[i+1:]
            k -= i + 1
        }
    }
}
 
func main() {
    for i := 0; ; i++ {
        v := []int{9, 8, 7, 6, 5, 0, 1, 2, 3, 4}
        if i == len(v) {
            return
        }
        fmt.Println(quickselect(v, i))
    }
}