implement insertion in Red-Black_Trees.cpp

Author: ashwek

3_Data_Structures/13_Red-Black_Trees/Red-Black_Trees.cpp

@@ -11,61 +11,175 @@ remains approximately balanced during insertions and deletions.
 
 #include <iostream>
 #include <vector>
+#include <stdlib.h>
 
 using namespace std;
 
-class Node{
+enum colors{RED, BLACK};
 
- public:
- Node *parent, *left, *right;
- int value, colour;
- //Colour : 0-Black, 1-Red
-
- Node(Node *parent, int value, Node *left, Node *right, int colour = 1){
- this->parent = parent;
- this->value = value;
- this->left = left;
- this->right = right;
- this->colour = colour;
- }
+class Node{
+public:
+ Node *parent, *left, *right;
+ int value;
+ colors node_color;
+ //Colour : 0-Black, 1-Red
+
+ Node(Node *parent, int value, Node *left, Node *right, colors node_color = RED){
+ this->parent = parent;
+ this->value = value;
+ this->left = left;
+ this->right = right;
+ this->node_color = node_color;
+ }
 };
 
 class RBT{
+public:
+ Node *nill = new Node(NULL, 0, NULL, NULL, BLACK); // NULL Node
+ Node *root = NULL;
+
+ RBT(){
+ root = NULL;
+ }
+
+ void inorder(Node *current = NULL){
+ if( current == NULL ) current = root;
+
+ // In-Order = (Left, Root, Right)
+ if( current != nill ){
+ if( current->left != nill ) inorder(current->left);
+ cout<<"(" <<current->value <<" " <<((current->node_color == RED) ? "R" : "B") <<"), ";
+ if( current->right != nill ) inorder(current->right);
+ }
+ }
+
+ void left_rotate(Node *node) {
+
+ Node *childNode = node->right;
+ Node *parentNode = node->parent;
+
+ node->right = childNode->left;
+ if( node->right != nill ){
+ node->right->parent = node;
+ }
+ childNode->left = node;
+ node->parent = childNode;
 
- public:
- Node *nill = new Node(NULL, 0, NULL, NULL, 0); // NULL Node
- Node *root = NULL;
+ if( node == root ){
+ root = childNode;
+ childNode->parent = nill;
+ }
+ else {
+ if( node == parentNode->left) parentNode->left = childNode;
+ else parentNode->right = childNode;
+ childNode->parent = parentNode;
+ }
+
+ }
+
+ void right_rotate(Node *node) {
 
- RBT(){
- root = NULL;
+ Node *childNode = node->left;
+ Node *parentNode = node->parent;
+
+ node->left = childNode->right;
+ if( node->left != nill ){
+ node->left->parent = node;
+ }
+ childNode->right = node;
+ node->parent = childNode;
+
+ if( root == node ) {
+ root = childNode;
+ childNode->parent = nill;
+ }
+ else {
+ if( parentNode->left == node ) parentNode->left = childNode;
+ else parentNode->right = childNode;
+ childNode->parent = parentNode;
  }
 
- void insert(int value){
- if( root == NULL ) root = new Node(nill, value, nill, nill, 0);
- else{
- Node *temp_parent = root, *temp = root;
- while( temp != nill ){
- temp_parent = temp;
- temp = ( value <= temp->value ) ? temp->left : temp->right;
+ }
+
+ void insert_fixup(Node *node) {
+
+ while( node->parent->node_color == RED ){
+
+ if( node->parent == node->parent->parent->left ){
+ Node *uncleNode = node->parent->parent->right;
+ if( uncleNode->node_color == RED ){
+ node->parent->node_color = uncleNode->node_color = BLACK;
+ node->parent->parent->node_color = RED;
+ node = node->parent->parent;
+ }
+ else {
+ if( node == node->parent->right ) {
+ node = node->parent;
+ left_rotate(node);
+ }
+ node->parent->node_color = BLACK;
+ node->parent->parent->node_color = RED;
+ right_rotate(node->parent->parent);
  }
+ }
+ else if( node->parent == node->parent->parent->right ){
+ Node *uncleNode = node->parent->parent->left;
+ if( uncleNode->node_color == RED ){
+ node->parent->node_color = uncleNode->node_color = BLACK;
+ node->parent->parent->node_color = RED;
+ node = node->parent->parent;
+ }
+ else {
+ if( node == node->parent->left ) {
+ node = node->parent;
+ right_rotate(node);
+ }
+ node->parent->node_color = BLACK;
+ node->parent->parent->node_color = RED;
+ left_rotate(node->parent->parent);
+ }
+ }
+ }
+
+ root->node_color = BLACK;
 
- Node *new_node = new Node(temp_parent, value, nill, nill);
- if( value <= temp_parent->value ) temp_parent->left = new_node;
- else temp_parent->right = new_node;
+ }
 
- //Call fixup method
+ void insert(int value){
+ if( root == NULL ) root = new Node(nill, value, nill, nill, BLACK);
+ else{
+ Node *temp_parent = root, *temp = root;
+ while( temp != nill ){
+ temp_parent = temp;
+ temp = ( value <= temp->value ) ? temp->left : temp->right;
  }
+
+ Node *new_node = new Node(temp_parent, value, nill, nill, RED);
+ if( value <= temp_parent->value ) temp_parent->left = new_node;
+ else temp_parent->right = new_node;
+
+ insert_fixup(new_node);
  }
+ }
+
 };
 
 int main(){
 
- int ins_values[] ={33, 65, 50, 55, 42, 31, 15, 65, 22, 87};
+ srand(0);
+ int temp;
  RBT a;
 
- for(int i=0; i<10; i++)
- a.insert(ins_values[i]);
+ for(int i = 0; i < 10; i++) {
+ temp = random() % 200 + 1;
+ cout <<"\nInserting " <<temp;
+ a.insert(temp);
+ }
+
+ cout <<"\n\nInorder : ";
+ a.inorder();
 
  cout<<endl;
  return 0;
+
 }