Answer to Go Playground Exercise

playground-concurency-exercise.go

// https://tour.golang.org/concurrency/8
package main

import "golang.org/x/tour/tree"
import "fmt"
// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch chan int) {
  // we need to close channel, so it need to call separately
	recursiveWalk(t, ch)
	close(ch) // to stop the range
}

// visit every leaf from the left 
func recursiveWalk(t *tree.Tree, ch chan int) {
	if t != nil {
		recursiveWalk(t.Left, ch) // go for Left leaf first!
		// send value to channel
		ch <- t.Value
		recursiveWalk(t.Right, ch)
	}
}

// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
	el1 := make(chan int) // channel for t1
	el2 := make(chan int) // channel for t2
	go Walk(t1, el1) // walk into t1
	go Walk(t2, el2) // walk into t2
	for {
    // wait for channel notif
		v1,ok1 := <-el1
		v2,ok2 := <-el2
		if ok1 && ok2 {
			if v1 != v2 {
				return false
			}
		} else if !ok1 && !ok2 {
			// both of channel  are empty!
			return true
		}
	}
	return false
}

func main() {
	a := tree.New(2)
	walker := make(chan int)
	go Walk(a, walker)
	for v := range walker {
		fmt.Print(v,"|")
	}
	fmt.Println(Same(tree.New(1), tree.New(1)))
	fmt.Println(Same(tree.New(1), tree.New(2)))
}