我正在尝试使用此代码查找二叉树的高度，但是它始终返回0，有人可以告诉我为什么吗？
int heightHelper(Node* root, int maxheight, int rootheight)
{
if (root->right == nullptr && root->left == nullptr) { //checks if the node has a child
if (maxheight < rootheight) {
maxheight = rootheight;
}
}
else { //if it has then increase height by 1
rootheight += 1;
if (root->left != nullptr) {
heightHelper(root->left, maxheight, rootheight);
}
if (root->right != nullptr) {
heightHelper(root->right, maxheight, rootheight);
}
}
return maxheight; //return height
}
int height(Node* root)
{
// Write your code here.
return heightHelper(root, 0, 0); //root node base case
}
您正在混淆两种处理方式。任一结果传递参数，使用指针或地址（int*和&maxheight）。在这种情况下，没有返回值。但是，这是一种编码风格，我主要只在硬件编程中才能看到。
否则，您可以返回结果。您已经有一个返回参数，只需修正该值的实际用法即可，因为您的代码将忽略它。
这是两种方法：
使用返回参数：
int heightHelper(Node* root, int height)
{
if (root->right == nullptr && root->left == nullptr) { //checks if the node has a child
return height;
}
else { //if it has then increase height by 1
height += 1;
int maxheight1;
int maxheight2;
if (root->left != nullptr) {
maxheight1 = heightHelper(root->left, height);
}
if (root->right != nullptr) {
maxheight2 = heightHelper(root->right, height);
}
// return maximum of the two
if (maxheight1 > maxheight2) return maxheight1;
else return maxheight2;
}
}
int height(Node* root)
{
// Write your code here.
return heightHelper(root, height); //root node base case
}
使用指针参数。请注意，rootheight对于每个分支都是局部的，因此请勿将其作为指针传递。
void heightHelper(Node* root, int* maxheight_ptr, int rootheight)
{
if (root->right == nullptr && root->left == nullptr) { //checks if the node has a child
if (*maxheight < rootheight) {
*maxheight = rootheight;
}
}
else { //if it has then increase height by 1
rootheight += 1;
if (root->left != nullptr) {
heightHelper(root->left, maxheight_ptr, rootheight);
}
if (root->right != nullptr) {
heightHelper(root->right, maxheight_ptr, rootheight);
}
}
}
int height(Node* root)
{
// Write your code here.
int maxheight = 0;
heightHelper(root, &maxheight, 0); //pass the addresses of variables
return maxheight;
}
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