statuses no recursion

statuses_no_recursion.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"
)

type Comment struct {
	id     int
	parent int
	msg    string
	indent int
}

func main() {
	for _, comment := range Rearrange(ParseInput(os.Stdin)) {
		fmt.Printf("%s- %d %s\n", strings.Repeat("  ", comment.indent), comment.id, comment.msg)
	}
}

func Rearrange(comments []Comment) []Comment {
	result := make([]Comment, 0, len(comments))
	for i := 0; i < len(comments); i++ {
		comment := comments[i]

		// find last child
		var found bool
		var lastChildIndex int
		for j := 0; j < len(result); j++ {
			if comment.parent == result[j].id {
				found = true
				lastChildIndex = j + 1
				parentIndent := result[j].indent
				for lastChildIndex < len(result) && (result[lastChildIndex].parent == comment.parent || result[lastChildIndex].indent > parentIndent) {
					lastChildIndex++
				}
				break
			}
		}

		// count indent
		var indent int
		for c := comment; c.parent != 0; {
			c = comments[c.parent-1]
			indent++
		}

		comment.indent = indent

		if found {
			prefix := make([]Comment, len(result[:lastChildIndex]))
			copy(prefix, result[:lastChildIndex])
			suffix := make([]Comment, len(result[lastChildIndex:]))
			copy(suffix, result[lastChildIndex:])
			result = append(prefix, comment)
			result = append(result, suffix...)
		} else {
			result = append(result, comment)
		}
	}
	return result
}

func ParseInput(r io.Reader) (comments []Comment) {
	scanner := bufio.NewScanner(r)
	if scanner.Scan() {
		n, _ := strconv.Atoi(scanner.Text())
		comments = make([]Comment, n)
		for i := 0; i < n; i++ {
			scanner.Scan()
			line := strings.Split(scanner.Text(), " ")
			parent, _ := strconv.Atoi(line[0])
			comments[i] = Comment{parent: parent, id: i + 1, msg: line[1]}
		}
	}
	return
}