cpp-interview/DataStructure/RedBlackTree.cpp

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#define BLACK 1
#define RED 0
#include <iostream>
using namespace std;
class bst {
private:
struct Node {
int value;
bool color;
Node *leftTree, *rightTree, *parent;
Node() : value(0), color(RED), leftTree(NULL), rightTree(NULL), parent(NULL) { }
Node* grandparent() {
if(parent == NULL){
return NULL;
}
return parent->parent;
}
Node* uncle() {
if(grandparent() == NULL) {
return NULL;
}
if(parent == grandparent()->rightTree)
return grandparent()->leftTree;
else
return grandparent()->rightTree;
}
Node* sibling() {
if(parent->leftTree == this)
return parent->rightTree;
else
return parent->leftTree;
}
};
void rotate_right(Node *p){
Node *gp = p->grandparent();
Node *fa = p->parent;
Node *y = p->rightTree;
fa->leftTree = y;
if(y != NIL)
y->parent = fa;
p->rightTree = fa;
fa->parent = p;
if(root == fa)
root = p;
p->parent = gp;
if(gp != NULL){
if(gp->leftTree == fa)
gp->leftTree = p;
else
gp->rightTree = p;
}
}
void rotate_left(Node *p){
if(p->parent == NULL){
root = p;
return;
}
Node *gp = p->grandparent();
Node *fa = p->parent;
Node *y = p->leftTree;
fa->rightTree = y;
if(y != NIL)
y->parent = fa;
p->leftTree = fa;
fa->parent = p;
if(root == fa)
root = p;
p->parent = gp;
if(gp != NULL){
if(gp->leftTree == fa)
gp->leftTree = p;
else
gp->rightTree = p;
}
}
void inorder(Node *p){
if(p == NIL)
return;
if(p->leftTree)
inorder(p->leftTree);
cout << p->value << " ";
if(p->rightTree)
inorder(p->rightTree);
}
string outputColor (bool color) {
return color ? "BLACK" : "RED";
}
Node* getSmallestChild(Node *p){
if(p->leftTree == NIL)
return p;
return getSmallestChild(p->leftTree);
}
bool delete_child(Node *p, int data){
if(p->value > data){
if(p->leftTree == NIL){
return false;
}
return delete_child(p->leftTree, data);
} else if(p->value < data){
if(p->rightTree == NIL){
return false;
}
return delete_child(p->rightTree, data);
} else if(p->value == data){
if(p->rightTree == NIL){
delete_one_child (p);
return true;
}
Node *smallest = getSmallestChild(p->rightTree);
swap(p->value, smallest->value);
delete_one_child (smallest);
return true;
}else{
return false;
}
}
void delete_one_child(Node *p){
Node *child = p->leftTree == NIL ? p->rightTree : p->leftTree;
if(p->parent == NULL && p->leftTree == NIL && p->rightTree == NIL){
p = NULL;
root = p;
return;
}
if(p->parent == NULL){
delete p;
child->parent = NULL;
root = child;
root->color = BLACK;
return;
}
if(p->parent->leftTree == p){
p->parent->leftTree = child;
} else {
p->parent->rightTree = child;
}
child->parent = p->parent;
if(p->color == BLACK){
if(child->color == RED){
child->color = BLACK;
} else
delete_case (child);
}
delete p;
}
void delete_case(Node *p){
if(p->parent == NULL){
p->color = BLACK;
return;
}
if(p->sibling()->color == RED) {
p->parent->color = RED;
p->sibling()->color = BLACK;
if(p == p->parent->leftTree)
rotate_left(p->sibling());
else
rotate_right(p->sibling());
}
if(p->parent->color == BLACK && p->sibling()->color == BLACK
&& p->sibling()->leftTree->color == BLACK && p->sibling()->rightTree->color == BLACK) {
p->sibling()->color = RED;
delete_case(p->parent);
} else if(p->parent->color == RED && p->sibling()->color == BLACK
&& p->sibling()->leftTree->color == BLACK && p->sibling()->rightTree->color == BLACK) {
p->sibling()->color = RED;
p->parent->color = BLACK;
} else {
if(p->sibling()->color == BLACK) {
if(p == p->parent->leftTree && p->sibling()->leftTree->color == RED
&& p->sibling()->rightTree->color == BLACK) {
p->sibling()->color = RED;
p->sibling()->leftTree->color = BLACK;
rotate_right(p->sibling()->leftTree);
} else if(p == p->parent->rightTree && p->sibling()->leftTree->color == BLACK
&& p->sibling()->rightTree->color == RED) {
p->sibling()->color = RED;
p->sibling()->rightTree->color = BLACK;
rotate_left(p->sibling()->rightTree);
}
}
p->sibling()->color = p->parent->color;
p->parent->color = BLACK;
if(p == p->parent->leftTree){
p->sibling()->rightTree->color = BLACK;
rotate_left(p->sibling());
} else {
p->sibling()->leftTree->color = BLACK;
rotate_right(p->sibling());
}
}
}
void insert(Node *p, int data){
if(p->value >= data){
if(p->leftTree != NIL)
insert(p->leftTree, data);
else {
Node *tmp = new Node();
tmp->value = data;
tmp->leftTree = tmp->rightTree = NIL;
tmp->parent = p;
p->leftTree = tmp;
insert_case (tmp);
}
} else {
if(p->rightTree != NIL)
insert(p->rightTree, data);
else {
Node *tmp = new Node();
tmp->value = data;
tmp->leftTree = tmp->rightTree = NIL;
tmp->parent = p;
p->rightTree = tmp;
insert_case (tmp);
}
}
}
void insert_case(Node *p){
if(p->parent == NULL){
root = p;
p->color = BLACK;
return;
}
if(p->parent->color == RED){
if(p->uncle()->color == RED) {
p->parent->color = p->uncle()->color = BLACK;
p->grandparent()->color = RED;
insert_case(p->grandparent());
} else {
if(p->parent->rightTree == p && p->grandparent()->leftTree == p->parent) {
rotate_left (p);
rotate_right (p);
p->color = BLACK;
p->leftTree->color = p->rightTree->color = RED;
} else if(p->parent->leftTree == p && p->grandparent()->rightTree == p->parent) {
rotate_right (p);
rotate_left (p);
p->color = BLACK;
p->leftTree->color = p->rightTree->color = RED;
} else if(p->parent->leftTree == p && p->grandparent()->leftTree == p->parent) {
p->parent->color = BLACK;
p->grandparent()->color = RED;
rotate_right(p->parent);
} else if(p->parent->rightTree == p && p->grandparent()->rightTree == p->parent) {
p->parent->color = BLACK;
p->grandparent()->color = RED;
rotate_left(p->parent);
}
}
}
}
void DeleteTree(Node *p){
if(!p || p == NIL){
return;
}
DeleteTree(p->leftTree);
DeleteTree(p->rightTree);
delete p;
}
public:
bst() {
NIL = new Node();
NIL->color = BLACK;
root = NULL;
}
~bst() {
if (root)
DeleteTree (root);
delete NIL;
}
void inorder() {
if(root == NULL)
return;
inorder (root);
cout << endl;
}
void insert (int x) {
if(root == NULL){
root = new Node();
root->color = BLACK;
root->leftTree = root->rightTree = NIL;
root->value = x;
} else {
insert(root, x);
}
}
bool delete_value (int data) {
return delete_child(root, data);
}
private:
Node *root, *NIL;
};