
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


Task

Implement a permutation sort, which proceeds by generating the possible permutations
of the input array/list until discovering the sorted one.

Pseudocode:

while not InOrder(list) do
    nextPermutation(list)
done



package main
 
import "fmt"
 
var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
 
// in place permutation sort of slice a
func main() {
    fmt.Println("before:", a)
    if len(a) > 1 && !recurse(len(a) - 1) {
        // recurse should never return false from the top level.
        // if it does, it means some code somewhere is busted,
        // either the the permutation generation code or the
        // sortedness testing code.
        panic("sorted permutation not found!")
    }
    fmt.Println("after: ", a)
}
 
// recursive permutation generator
func recurse(last int) bool {
    if last <= 0 {
        // bottom of recursion.  test if sorted.
        for i := len(a) - 1; a[i] >= a[i-1]; i-- {
            if i == 1 {
                return true
            }
        }
        return false
    }
    for i := 0; i <= last; i++ {
        a[i], a[last] = a[last], a[i]
        if recurse(last - 1) {
            return true
        }
        a[i], a[last] = a[last], a[i]
    }
    return false
}