Exercise: Equivalent Binary Trees (https://tour.golang.org/concurrency/8)

equivalent_binary_tree.go

package main

import (
	"golang.org/x/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) {
	var walk func(t *tree.Tree)
	walk = func(t *tree.Tree) {
		if t.Left != nil {
			walk(t.Left)
		}
		ch <- t.Value
		if t.Right != nil {
			walk(t.Right)
		}
	}
	
	walk(t)
	close(ch)
}

// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
	ch1, ch2 := make(chan int), make(chan int)
	go Walk(t1, ch1)
	go Walk(t2, ch2)
	
	for {
		v1, ok1 := <- ch1
		v2, ok2 := <- ch2
		// fmt.Printf("v1, ok1 = %d, %s    v2, ok2 = %d, %s", v1, ok1, v2, ok2)
		if v1 != v2 || ok1 != ok2 {
			return false
		}
		if ok1 == ok2 && !ok1 {
			break
		}
	}
	return true
}

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