Javascript 如何遍历两个相同的树并返回目标值？

有人能告诉我为什么console.log输出正确的答案，但是返回值为null吗

我尝试遍历两个相同的树，然后当在原始树的节点中找到目标值时，我尝试在克隆树中返回相同的节点值

我真的很感激你能提供的任何帮助

原始问题：

代码库：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    original.left = getTargetCopy(original.left, cloned.left, target)
    original.right = getTargetCopy(original.right, cloned.right, target)
    
    if(original.val === target.val) {
        console.log(cloned.val)
        return cloned.val
    }
};

Your input:
original = [7,4,3,null,null,6,19]
cloned = [7,4,3,null,null,6,19]
target.val = 3

stdout:
3

Output:
null

Expected:
3

输入：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    original.left = getTargetCopy(original.left, cloned.left, target)
    original.right = getTargetCopy(original.right, cloned.right, target)
    
    if(original.val === target.val) {
        console.log(cloned.val)
        return cloned.val
    }
};

Your input:
original = [7,4,3,null,null,6,19]
cloned = [7,4,3,null,null,6,19]
target.val = 3

stdout:
3

Output:
null

Expected:
3

控制台。日志：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    original.left = getTargetCopy(original.left, cloned.left, target)
    original.right = getTargetCopy(original.right, cloned.right, target)
    
    if(original.val === target.val) {
        console.log(cloned.val)
        return cloned.val
    }
};

Your input:
original = [7,4,3,null,null,6,19]
cloned = [7,4,3,null,null,6,19]
target.val = 3

stdout:
3

Output:
null

Expected:
3

输出：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    original.left = getTargetCopy(original.left, cloned.left, target)
    original.right = getTargetCopy(original.right, cloned.right, target)
    
    if(original.val === target.val) {
        console.log(cloned.val)
        return cloned.val
    }
};

Your input:
original = [7,4,3,null,null,6,19]
cloned = [7,4,3,null,null,6,19]
target.val = 3

stdout:
3

Output:
null

Expected:
3

所需答案：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    original.left = getTargetCopy(original.left, cloned.left, target)
    original.right = getTargetCopy(original.right, cloned.right, target)
    
    if(original.val === target.val) {
        console.log(cloned.val)
        return cloned.val
    }
};

Your input:
original = [7,4,3,null,null,6,19]
cloned = [7,4,3,null,null,6,19]
target.val = 3

stdout:
3

Output:
null

Expected:
3

一些问题：

函数应该返回一个节点，而不是一个值，因此

return cloned.val

是错误的。它应该是

返回克隆的

使用以下语句可以对原始树进行变异：

original.left = getTargetCopy(original.left, cloned.left, target)
original.right = getTargetCopy(original.right, cloned.right, target)

这不应该发生

使用

if（original.val==target.val）

当

target.val

不是唯一值时，代码可能会出现误报。相反，您应该比较节点引用

当您有一个匹配项时，您不必进行更深层次的递归，因此在执行递归调用之前执行此测试

当递归调用返回一个节点时，您应该立即返回该节点，而不执行任何其他递归调用

以下是您的代码更正：

var getTargetCopy = function(original, cloned, target) {
    if(original === null) {
        return null
    }
    
    if(original === target) {
        return cloned;
    }

    return getTargetCopy(original.left, cloned.left, target)
            || getTargetCopy(original.right, cloned.right, target)
    
};

使其更加浓缩，可以是：

var getTargetCopy = (original, cloned, target) =>
    !original || original === target 
        ? cloned
        : getTargetCopy(original.left, cloned.left, target)
          || getTargetCopy(original.right, cloned.right, target);

---

数据中的树在哪里？@NinaScholz这是二叉树节点的定义方式：函数TreeNode（val）{This.val=val；This.left=This.right=null；}@NinaScholz我添加了指向我试图解决的leetcode问题的链接。感谢您的深入回答！我担心我不会得到任何解释，因为有人否决了这篇文章。你能帮助我理解当我克隆控制台日志时，为什么我得到一个数组而不是int？你没有得到数组，而是一个对象（用大括号显示）。int在

cloned

的属性中可用：

cloned.val

。能否详细说明此代码块的作用？“return getTargetCopy（original.left，cloned.left，target）| getTargetCopy（original.right，cloned.right，target）”是否正在遍历树？再次感谢你。