http://go-tour-jp.appspot.com/#70

gistfile1.go

package main

import (
	"code.google.com/p/go-tour/tree"
	"fmt"
)

// Walk walks the tree t sending all values
// from the tree to the channel ch.

func Walk(t *tree.Tree, ch chan int) {
	subWalk(t, ch)
	close(ch)
}

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

func zip(ch1, ch2 chan int, out chan bool) {
	var v1, v2 int
	var ok1, ok2 bool
	for {
		select {
		case v1, ok1 = <-ch1:
			if !ok1 {
				close(out)
				return
			}
			v2, ok2 = <-ch2
			if !ok2 {
				close(out)
				return
			}
		case v2, ok2 = <-ch2:
			if !ok2 {
				close(out)
				return
			}
			v1, ok1 = <-ch1
			if !ok1 {
				close(out)
				return
			}
		}
		out <- v1 == v2
	}
}

// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
	ch1 := make(chan int, 100)
	ch2 := make(chan int, 100)
	ch3 := make(chan bool, 100)

	go Walk(t1, ch1)
	go Walk(t2, ch2)
	go zip(ch1, ch2, ch3)

	for v := range ch3 {
		if !v {
			return false
		}
	}
	return true
}

func main() {
	if Same(tree.New(10), tree.New(10)) {
		fmt.Println("yay")
	} else {
		fmt.Println("oh...")
	}
}

gistfile2.txt

yay

Program exited.