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Jul 16, 2018
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Red Black Tree Implementation (Java) #428

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330 changes: 330 additions & 0 deletions Data Structures/Trees/RedBlackBST.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,330 @@
/**
*
* @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;
}
}

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);
}
}