JavaAlgorithms/DataStructures/Trees/RedBlackBST.java

package DataStructures.Trees;

import java.util.Scanner;

/** @author jack870131 */
public class RedBlackBST {

  private final int R = 0;
  private final int B = 1;

  private class Node {

    int key = -1, color = B;
    Node left = nil, right = nil, p = nil;

    Node(int key) {
      this.key = key;
    }
  }

  private final Node nil = new Node(-1);
  private Node root = nil;

  public void printTree(Node node) {
    if (node == nil) {
      return;
    }
    printTree(node.left);
    System.out.print(
        ((node.color == R) ? " R " : " B ") + "Key: " + node.key + " Parent: " + node.p.key + "\n");
    printTree(node.right);
  }

  public void printTreepre(Node node) {
    if (node == nil) {
      return;
    }
    System.out.print(
        ((node.color == R) ? " R " : " B ") + "Key: " + node.key + " Parent: " + node.p.key + "\n");
    printTree(node.left);
    printTree(node.right);
  }

  private Node findNode(Node findNode, Node node) {
    if (root == nil) {
      return null;
    }
    if (findNode.key < node.key) {
      if (node.left != nil) {
        return findNode(findNode, node.left);
      }
    } else if (findNode.key > node.key) {
      if (node.right != nil) {
        return findNode(findNode, node.right);
      }
    } else if (findNode.key == node.key) {
      return node;
    }
    return null;
  }

  private void insert(Node node) {
    Node temp = root;
    if (root == nil) {
      root = node;
      node.color = B;
      node.p = nil;
    } else {
      node.color = R;
      while (true) {
        if (node.key < temp.key) {
          if (temp.left == nil) {
            temp.left = node;
            node.p = temp;
            break;
          } else {
            temp = temp.left;
          }
        } else if (node.key >= temp.key) {
          if (temp.right == nil) {
            temp.right = node;
            node.p = temp;
            break;
          } else {
            temp = temp.right;
          }
        }
      }
      fixTree(node);
    }
  }

  private void fixTree(Node node) {
    while (node.p.color == R) {
      Node y = nil;
      if (node.p == node.p.p.left) {
        y = node.p.p.right;

        if (y != nil && y.color == R) {
          node.p.color = B;
          y.color = B;
          node.p.p.color = R;
          node = node.p.p;
          continue;
        }
        if (node == node.p.right) {
          node = node.p;
          rotateLeft(node);
        }
        node.p.color = B;
        node.p.p.color = R;
        rotateRight(node.p.p);
      } else {
        y = node.p.p.left;
        if (y != nil && y.color == R) {
          node.p.color = B;
          y.color = B;
          node.p.p.color = R;
          node = node.p.p;
          continue;
        }
        if (node == node.p.left) {
          node = node.p;
          rotateRight(node);
        }
        node.p.color = B;
        node.p.p.color = R;
        rotateLeft(node.p.p);
      }
    }
    root.color = B;
  }

  void rotateLeft(Node node) {
    if (node.p != nil) {
      if (node == node.p.left) {
        node.p.left = node.right;
      } else {
        node.p.right = node.right;
      }
      node.right.p = node.p;
      node.p = node.right;
      if (node.right.left != nil) {
        node.right.left.p = node;
      }
      node.right = node.right.left;
      node.p.left = node;
    } else {
      Node right = root.right;
      root.right = right.left;
      right.left.p = root;
      root.p = right;
      right.left = root;
      right.p = nil;
      root = right;
    }
  }

  void rotateRight(Node node) {
    if (node.p != nil) {
      if (node == node.p.left) {
        node.p.left = node.left;
      } else {
        node.p.right = node.left;
      }

      node.left.p = node.p;
      node.p = node.left;
      if (node.left.right != nil) {
        node.left.right.p = node;
      }
      node.left = node.left.right;
      node.p.right = node;
    } else {
      Node left = root.left;
      root.left = root.left.right;
      left.right.p = root;
      root.p = left;
      left.right = root;
      left.p = nil;
      root = left;
    }
  }

  void transplant(Node target, Node with) {
    if (target.p == nil) {
      root = with;
    } else if (target == target.p.left) {
      target.p.left = with;
    } else target.p.right = with;
    with.p = target.p;
  }

  Node treeMinimum(Node subTreeRoot) {
    while (subTreeRoot.left != nil) {
      subTreeRoot = subTreeRoot.left;
    }
    return subTreeRoot;
  }

  boolean delete(Node z) {
    if ((z = findNode(z, root)) == null) return false;
    Node x;
    Node y = z;
    int yorigcolor = y.color;

    if (z.left == nil) {
      x = z.right;
      transplant(z, z.right);
    } else if (z.right == nil) {
      x = z.left;
      transplant(z, z.left);
    } else {
      y = treeMinimum(z.right);
      yorigcolor = y.color;
      x = y.right;
      if (y.p == z) x.p = y;
      else {
        transplant(y, y.right);
        y.right = z.right;
        y.right.p = y;
      }
      transplant(z, y);
      y.left = z.left;
      y.left.p = y;
      y.color = z.color;
    }
    if (yorigcolor == B) deleteFixup(x);
    return true;
  }

  void deleteFixup(Node x) {
    while (x != root && x.color == B) {
      if (x == x.p.left) {
        Node w = x.p.right;
        if (w.color == R) {
          w.color = B;
          x.p.color = R;
          rotateLeft(x.p);
          w = x.p.right;
        }
        if (w.left.color == B && w.right.color == B) {
          w.color = R;
          x = x.p;
          continue;
        } else if (w.right.color == B) {
          w.left.color = B;
          w.color = R;
          rotateRight(w);
          w = x.p.right;
        }
        if (w.right.color == R) {
          w.color = x.p.color;
          x.p.color = B;
          w.right.color = B;
          rotateLeft(x.p);
          x = root;
        }
      } else {
        Node w = x.p.left;
        if (w.color == R) {
          w.color = B;
          x.p.color = R;
          rotateRight(x.p);
          w = x.p.left;
        }
        if (w.right.color == B && w.left.color == B) {
          w.color = R;
          x = x.p;
          continue;
        } else if (w.left.color == B) {
          w.right.color = B;
          w.color = R;
          rotateLeft(w);
          w = x.p.left;
        }
        if (w.left.color == R) {
          w.color = x.p.color;
          x.p.color = B;
          w.left.color = B;
          rotateRight(x.p);
          x = root;
        }
      }
    }
    x.color = B;
  }

  public void insertDemo() {
    Scanner scan = new Scanner(System.in);
    while (true) {
      System.out.println("Add items");

      int item;
      Node node;

      item = scan.nextInt();
      while (item != -999) {
        node = new Node(item);
        insert(node);
        item = scan.nextInt();
      }
      printTree(root);
      System.out.println("Pre order");
      printTreepre(root);
      break;
    }
    scan.close();
  }

  public void deleteDemo() {
    Scanner scan = new Scanner(System.in);
    System.out.println("Delete items");
    int item;
    Node node;
    item = scan.nextInt();
    node = new Node(item);
    System.out.print("Deleting item " + item);
    if (delete(node)) {
      System.out.print(": deleted!");
    } else {
      System.out.print(": does not exist!");
    }

    System.out.println();
    printTree(root);
    System.out.println("Pre order");
    printTreepre(root);
    scan.close();
  }
}