Go implementation with non-JSON input

petowner_1.go

package main

import "fmt"

type Pet struct {
	Owner string `json:"owner"`
	Pet   string `json:"pet"`
}

func main() {
	input := []Pet{
		{Owner: "Kent", Pet: "Shiner"},
		{Owner: "Mary", Pet: "Pumpkin"},
		{Owner: "Mary", Pet: "Tasha"},
		{Owner: "Paige", Pet: "Sushi"},
		{Owner: "Sarah", Pet: "Shiner"},
		{Owner: "Sarah", Pet: "Mr. Wigglesworth"},
		{Owner: "Sarah", Pet: "Pupparoo"},
		{Owner: "Sarah", Pet: "Lucy"},
	}

	output := make(map[string][]string)
	for _, pair := range input {
		output[pair.Owner] = append(output[pair.Owner], pair.Pet)
	}

	json.NewEncoder(os.Stdout).Encode(output)
}