gosort.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"regexp"
	"sort"
	"strconv"
)

func main() {
	if err := gosort(os.Stdin, os.Stdout); err != nil {
		panic(err)
	}
}

func gosort(r io.Reader, w io.Writer) error {
	re := regexp.MustCompile("(\\d+) minutes?\\]")
	s := bufio.NewScanner(r)
	type block struct {
		active int
		bytes  []byte
	}
	blocks := make([]block, 0)

	b := block{}
	add := func(bb block) {
		blocks = append(blocks, b)
		b = block{}
	}

	for {
		if !s.Scan() {
			add(b)
			break
		}
		row := s.Bytes()
		if len(row) == 0 {
			add(b)
			continue
		}
		if b.bytes == nil {
			if matches := re.FindSubmatch(row); len(matches) == 2 {
				min, err := strconv.Atoi(string(matches[1]))
				if err != nil {
					return err
				}
				b.active = min
			}
		}
		b.bytes = append(b.bytes, row...)
		b.bytes = append(b.bytes, '\n')
	}

	sort.Slice(blocks, func(i, j int) bool {
		return blocks[i].active < blocks[j].active
	})

	for _, r := range blocks {
		fmt.Printf("%s\n", r.bytes)
	}

	return nil
}