topologicalSort.go

//topological sort

package main

import (
	"fmt"
	"sort"
)

var pathOfFullstack = map[string][]string{
	"fullstack developer": {"C#", "Python", "Go", "Angular", "React"},
	"C#":      {"C"},
	"Angular": {"html", "Css", "Javascript"},
	"Go":      {"C#", "Python"},
	"React":   {"html", "Javascript", "JSX"},
}

func main() {
	for i, path := range topoSort(pathOfFullstack) {
		fmt.Printf("%d:\t%s\n", i+1, path)
	}
}

func topoSort(m map[string][]string) []string {
	var pathOrder []string
	visited := make(map[string]bool)
	var visitAll func(items []string)
	visitAll = func(items []string) {
		for _, item := range items {
			if !visited[item] {
				visited[item] = true
				visitAll(m[item])
				pathOrder = append(pathOrder, item)
			}
		}
	}
	var paths []string
	for devPath := range m {
		paths = append(paths, devPath)
	}
	sort.Strings(paths)
	visitAll(paths)
	return pathOrder
}


// Output 
/*

1:	html
2:	Css
3:	Javascript
4:	Angular
5:	C
6:	C#
7:	Python
8:	Go
9:	JSX
10:	React
11:	fullstack developer 

*/