golang https://tour.go-zh.org/methods/9的解决方案

Posted 2021-05-24

package main

import (
	"fmt"
)

func Sqrt(x float64) (float64, error) {
	var err ErrNegativeSqrt
	var z float64
	if x < 0 {
		err = ErrNegativeSqrt(x)
		return z, err
	} else {
		z = x
		for i := 0; i < 10; i++ {
			z = z - (z*z-x)/(2*z)
		}
		return z, nil
	}
}

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string {
	return fmt.Sprintf("cannot Sqrt negative number: %f", float64(e))
}

func main() {
	fmt.Println(Sqrt(2))
	fmt.Println(Sqrt(-2))
}

Go学习之实现等价二叉查找树

地址：https://tour.go-zh.org/concurrency/7

code：

package main

import (
	"golang.org/x/tour/tree"
	"fmt"
	//"strconv"
)

// Walk 步进 tree t 将所有的值从 tree 发送到 channel ch。
func Walk(t *tree.Tree, ch chan int) 
	if t == nil 
		return
	
	if t.Left != nil 
		Walk(t.Left, ch)		
	
	//fmt.Println(t.Value)
	ch <- t.Value
	if t.Right != nil 
		Walk(t.Right, ch)
	
	return


// Same 检测树 t1 和 t2 是否含有相同的值。
func Same(t1, t2 *tree.Tree) bool 
	ch0 := make(chan int, 15)
	ch1 := make(chan int, 15)
	Walk(t1, ch0)
	close(ch0)
	Walk(t2, ch1)
	close(ch1)
	l0 := len(ch0)
	l1 := len(ch1)
	if l0 != l1 
		return false;
	
	for i := 0; i < l0; i++ 
		if <-ch0 != <-ch1 
			return false
		
		//fmt.Println("ch0:" + strconv.Itoa(<-ch0))
	
	//for i := 0; i < l1; i++ 
	//	fmt.Println("ch1:" + strconv.Itoa(<-ch1))
	//
	return true


func main() 
	tree0 := tree.New(2)
	tree1 := tree.New(2)
	ret := Same(tree0, tree1)
	fmt.Println(ret)