[英]Removing a node with two children in a Binary Tree
这就是我到目前为止的代码。 我想我大部分时候都没有掌握逻辑,但是我被困在两个孩子的身上。.我弄清楚了我必须使用哪种算法才能使它起作用(我在注释中添加了注释在函数的底部),我只是不确定如何开始...有人能指出我正确的方向吗?
这是我到目前为止的内容:
void BinaryTree::remove(int data){
// Is the data valid?
if(data < 0){
cerr << data << " is not valid. Must be a positive integer value." << endl;
}
else{
// Find the node
BinNode* loc = root;
BinNode* parent = nullptr;
bool found = false;
while(!found && loc != nullptr){
if(data > loc->data){
parent = loc;
loc = loc->right;
}
else if(data < loc->data){
parent = loc;
loc = loc->left;
}
else found = true;
}
// If there is a parent, take care of the pointer
if(parent != nullptr){
if(loc->data < parent->data)
parent->left = nullptr;
else if(loc->data > parent->data)
parent->right = nullptr;
}
// If there are children, save pointers to them
BinNode* leftChild = nullptr;
BinNode* rightChild = nullptr;
if(loc->left != nullptr)
leftChild = loc->left;
if(loc->right != nullptr)
rightChild = loc->right;
// So now pointers to the children have been saved (if they exist) and
// parent pointers have been taken care of (if they exist) the node can be deleted
// If no children exist simply just delete the node and return
delete loc;
// If one child exists
if(leftChild != nullptr || rightChild != nullptr){
if(leftChild != nullptr){
if(leftChild->data < parent->data)
parent->left = leftChild;
else if(leftChild->data > parent->data)
parent->right = leftChild;
}
else if(rightChild != nullptr){
if(rightChild->data < parent->data)
parent->left = rightChild;
else if(rightChild->data > parent->data)
parent->right = rightChild;
}
}
// Both children exist...this sucks.
else if(leftChild != nullptr && rightChild != nullptr){
// Find a minimum in the right subtree
BinNode * min = root;
BinNode * minParent = nullptr;
while(min->left != nullptr){
minParent = min;
min = min->left;
}
// Replace value of the node to be removed with the found minimum
loc = new BinNode(min->data);
// Delete the remaining duplicate node
if(minParent != nullptr)
minParent->left = nullptr;
delete min;
}
}
}
我们来了。 这似乎有效。 如果有人对如何优化此问题或需要解决的问题有任何建议,请说出来! 谢谢!
void BinaryTree::remove(int data){
// Is the data valid?
if(data < 0){
cerr << data << " is not valid. Must be a positive integer value." << endl;
}
else{
// Find the node
BinNode* loc = root;
BinNode* parent = nullptr;
bool found = false;
while(!found && loc != nullptr){
if(data > loc->data){
parent = loc;
loc = loc->right;
}
else if(data < loc->data){
parent = loc;
loc = loc->left;
}
else found = true;
// If there are children, save pointers to them
BinNode* leftChild = nullptr;
BinNode* rightChild = nullptr;
if(loc->left != nullptr)
leftChild = loc->left;
if(loc->right != nullptr)
rightChild = loc->right;
// So now pointers to the children have been saved (if they exist) and
// parent pointers have been taken care of (if they exist) the node can be deleted
// If no children exist simply just delete the node and return
// Check if two children exist
if(leftChild != nullptr && rightChild != nullptr){
// Find a minimum in the right subtree
BinNode * min = loc->right;
BinNode * minParent = loc;
while(min->left != nullptr){
minParent = min;
min = min->left;
}
// Replace value of the node to be removed with the found minimum
loc->data = min->data;
// Delete the duplicate
if(minParent != loc)
minParent->left = nullptr;
else minParent->right = nullptr;
delete min;
}
// If one child exists
// Need to handle if it is the root here
// change root pointer to remaining child
else if(leftChild != nullptr || rightChild != nullptr){
// If there is a parent, take care of the pointer
if(parent != nullptr){
if(loc->data < parent->data)
parent->left = nullptr;
else if(loc->data > parent->data)
parent->right = nullptr;
// Now loc can be deleted
delete loc;
if(leftChild != nullptr){
if(parent != nullptr){
if(leftChild->data < parent->data)
parent->left = leftChild;
else if(leftChild->data > parent->data)
parent->right = leftChild;
}
// If it is the root
else{
root = leftChild;
}
}
else if(rightChild != nullptr){
if(parent != nullptr){
if(rightChild->data < parent->data)
parent->left = rightChild;
else if(rightChild->data > parent->data)
parent->right = rightChild;
}
// If it is the root
else{
root = rightChild;
}
}
}
// If there are no children
else if (leftChild == nullptr && rightChild == nullptr){
// If there is a parent, take care of the pointer
if(parent != nullptr){
if(loc->data < parent->data)
parent->left = nullptr;
else if(loc->data > parent->data)
parent->right = nullptr;
}
// If it is the root
else
root = nullptr;
delete loc;
}
}
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