tree - go code

tree.go

package tree

import (
	"fmt"
	"sort"
)

//Record sctruct holds initial records
type Record struct {
	ID     int
	Parent int
}

//Node represents a tree node
type Node struct {
	ID       int
	Children []*Node
}

//Build creates tree from given list of records
func Build(records []Record) (*Node, error) {
	nodes := make([]Node, len(records))
	if len(records) == 0 {
		return nil, nil
	}
        
	sort.Slice(records, func(i, j int) bool { return records[i].ID < records[j].ID })
	for _, n := range records {
		if n.ID != 0 {
			nodes[n.Parent].Children = append(nodes[n.Parent].Children, &nodes[n.ID])
		}
		nodes[n.ID].ID = n.ID
	}
	return &nodes[0], nil
}