So the problem I'm having is the insert method for an AVLtree. My avltree stores city objects, and I use the names of the cities to decide where they should go.
My City .cpp class:
#include "City.h"
#include <iostream>
using namespace std;
City::City(string name, string country, double lat, double lon){
this->name = name;
this->country = country;
this->latitude = lat;
this->longtitude = lon;
}
double City::getLatOfCity(void){
return this->latitude;
}
double City::getLonOfCity(void){
return this->longtitude;
}
string City::getName(void){
return this->name;
}
string City::getCountry(void){
return this->country;
}
The methods in my avltree .cpp file.
My rotate left method:
Node* AVLtree::rotateLeft(Node* node){
Node* tempParent= node->getParent();
Node* tempNode = node->getChildL();
node->setChildL(tempNode->getChildR());
tempNode->setChildR(node);
if(tempParent==0){tempNode->removeParent();this->rootNode=tempNode;}
else{tempParent->setChildL(tempNode);
//tempNode->updateParent(tempParent);
}
return tempNode;
}
Rotate right method:
Node* AVLtree::rotateRight(Node* node){
Node* tempParent = node->getParent();
if(tempParent!=0){cout<<"IHN";cout<<"temp parent: " << tempParent->getCity()->getName();}
Node* tempNode = node->getChildR();
node->setChildR(tempNode->getChildL());
tempNode->setChildL(node);
if(tempParent==0){tempNode->removeParent();this->rootNode=tempNode;}
else{tempParent->setChildR(tempNode);}
return tempNode;
}
My first double right rotation method. This one doesn't work properly as the pointers I pass into the rotate methods are different when inside the method.
/*
Node* AVLtree::rotateTwoRights(Node* node){
node = rotateRight(node->getChildR());
node = rotateRight(node->getParent());
return node;
} */
I know this is very messy, but it seems to correctly rotate the nodes around.
Node* AVLtree::rotateTwoRights(Node* node){
Node* tempParent = node;
Node* tempNode = node->getChildR();
Node* tempTempNode = tempNode->getChildL();
tempNode->setChildL(tempTempNode->getChildL());
tempTempNode->setChildR(tempNode);
tempParent->setChildR(tempTempNode);
Node* tempTempParent = tempParent->getParent();
tempTempParent->setChildR(tempParent->getChildL());
tempParent->setChildL(tempTempParent);
Node* newTempParent = tempParent->getParent();
if(newTempParent==0){tempParent->removeParent();this->rootNode=tempParent;}
else{newTempParent->setChildR(tempParent);}
return tempParent;
}
Same as my first rotate double right method, but for the left side. Same problems:
Node* AVLtree::rotateTwoLefts(Node* node){
node = rotateRight(node->getChildL());
node = rotateLeft(node);
return node;
}
My insert method:
Node* AVLtree::insertNode(Node* parent, Node* node, City *city, int side){
if(node == 0){
if(side==0){
node = parent->setChildL(new Node(city));
}else if(side==1){
node = parent->setChildR(new Node(city));
}
}else if(node->getCity()->getName().compare(city->getName())<0){ //Right case
parent = node;
node = insertNode(parent, node->getChildR(), city, 1);
if(parent->getBalance()==2){
if(parent->getChildR()->getCity()->getName().compare(city->getName())<0){
node = rotateRight(parent);
}else{
node = rotateTwoRights(parent);
}
}
}else if(node->getCity()->getName().compare(city->getName())>0){ //Left case
parent = node;
node = insertNode(parent, node->getChildL(), city, 0);
if(parent->getBalance()==-2){
if(parent->getChildL()->getCity()->getName().compare(city->getName())>0){
node = rotateLeft(parent);
}else{
node = rotateTwoLefts(parent);
}
}
}else{
node=0;
}
return node;
}
So the problem is when trying I try to insert a 'CA'.
So the tree would look like this:
B
/ \
A C
\
D
and after inserting 'CA', it should follow these steps:
1)
B
/ \
A C
\
D
/
CA
2)
B
/ \
A C
\
CA
\
D
3)
C
/ \
B CA
/ \
A D
What the error is that when I run test on it, the root of the tree is still B.
I believe it's due to parent, as it doesn't get updated when I rebalance the tree after the recursive call. However, when I assign parent to the return value of the method, then I can't even add 'C' to the tree.
I would be very grateful for any sort of help. I've spent a lot of time on this and really want to get this done.
I do apologize for the long post and messy code, and give my thanks in advance!
