很抱歉，这是我第一次在stackoverflow中提问。我刚刚阅读了常见问题解答，知道我违反了规则。我不仅仅是在应对和粘贴问题。我使用有序遍历方法进行递归，检查节点是否是5的倍数，我不知道接下来该做什么。我应该使用标志来检查什么吗？
void findNodes(BSTNode<Key,E> *root) const
{
if(root==NULL) return;
else
{
if(root->key()%5==0)//I know it's wrong, but I don't know what to do
{
findNodes(root->left());
cout<<root->key()<<" ";
findNodes(root->right());
}
else
{
findNodes(root->left());
findNodes(root->right());
}
}
}
打印祖父母是5的倍数的节点很复杂，因为您必须“查找”树。如果您将问题视为找到5的倍数的所有节点并打印它们的子节点，则会更容易，因为您只需沿着树往下走。
void printGrandChildren(BSTNode<Key,E> *root,int level) const{
if(!root) return;
if(level == 2){
cout<<root->key()<<" ";
return;
}else{
printGrandChildren(root->left(),level+1);
printGrandChildren(root->right(),level+1);
}
}
然后修改您的findNodes为
void findNodes(BSTNode<Key,E> *root) const
{
if(root==NULL) return;
else
{
if(root->key()%5==0)
{
printGrandChildren(root,0);
}
else
{
findNodes(root->left());
findNodes(root->right());
}
}
}
试试这个：
int arr[height_of_the_tree]; //arr[10000000] if needed;
void findNodes(BSTNode<Key,E> *root,int level) const {
if(root==NULL) return;
arr[level] = root -> key();
findNodes(root -> left(), level + 1);
if(2 <= level && arr[level - 2] % 5 == 0) cout << root->key() << " ";
findNodes(root -> right(), level + 1);
}
int main() {
...
findNodes(Binary_search_tree -> root,0);
...
}
替换以下内容
cout<<root->key()<<" ";
随着
if(root->left)
{
if(root->left->left)
cout<<root->left->left->key()<< " ";
if(root->left->right)
cout<<root->left->right->key()<< " ";
}
if(root->right)
{
if(root->right->left)
cout<<root->right->left->key()<< " ";
if(root->right->right)
cout<<root->right->right->key()<< " ";
}
