Go (golang) custom sort

custom_sort.go

package main

import (
	"fmt"
	"sort"
)

// Slices implements the Go standard lib's Sort interface
// by having Len, Less, and Swap methods.
// This particular demo implementation sorts multiple slices,
// keeping all ints in the same relative positions, but sorted
// based on the values of the first slice in the list of slices.
type Slices [][]int

func (s Slices) Len() int { return len(s[0]) }
func (s Slices) Less(i, j int) bool { return s[0][i] < s[0][j] }
func (s Slices) Swap(i, j int) {
	for sub := range s {
		s[sub][i], s[sub][j] = s[sub][j], s[sub][i]
	}
}

func main() {
	// for demo purposes, note that all ints in same original position have same second digit
	a := []int{22, 44, 11, 33}
	b := []int{52, 14, 91, 23}
	c := []int{92, 84, 71, 63}
	d := []int{12, 24, 31, 43}
	
	sort.Sort(Slices{a, b, c, d})
  
	fmt.Println("a", a)
	fmt.Println("b", b)
	fmt.Println("c", c)
	fmt.Println("d", d)
}

/* output:
a [11 22 33 44]
b [91 52 23 14]
c [71 92 63 84]
d [31 12 43 24]
*/
// note that sorted output still has all nums in same relative position as their corresponding
// "slice a" num; i.e., all second-digit-is-1 are first; all second-digit-is-2 are second, etc