package main

import "fmt"
import "golang.org/x/tour/tree"

func recWalk(t *tree.Tree, ch chan int) {
	if t.Left != nil {
		recWalk(t.Left,ch)
	}
	ch <- t.Value
	if t.Right != nil {
		recWalk(t.Right,ch)
	}	
}

// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch chan int) {
	recWalk(t,ch)
	close(ch)
}

// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
	ch1 := make(chan int)
	ch2 := make(chan int)

	go Walk(t1, ch1)
	go Walk(t2, ch2)

	for {
		v1, ok1 := <-ch1		
		v2, ok2 := <-ch2

		if !ok1 && !ok2 {
			break
		}

		if ok1 != ok2 {
			return false
		}
		
		if v1 != v2 {
			return false
		}		
	}

	return true
}

func main() {
	ch := make(chan int)

	go Walk(tree.New(1), ch)

	for i := range ch {
		fmt.Println(i)
	}	

	fmt.Println(Same(tree.New(1), tree.New(1))) 
	fmt.Println(Same(tree.New(1), tree.New(2))) 
}