// returns null if not there
private RedBlackNode findParent(int value) {
RedBlackNode tmp = root;
RedBlackNode prevPtr = null;
while (!tmp.isFake()) {
prevPtr = tmp;
if (value < tmp.getValue()) tmp = (RedBlackNode) tmp.getLeft();
else tmp = (RedBlackNode) tmp.getRight();
}
return prevPtr;
}
private RedBlackNode find(int value, RedBlackNode node) {
if (node.getValue() == value) {
return node;
} else if (value < node.getValue()) {
if (!((RedBlackNode) node.getLeft()).isFake()) {
return find(value, (RedBlackNode) node.getLeft());
}
} else if (value > node.getValue()) {
if (!((RedBlackNode) node.getRight()).isFake()) {
return find(value, (RedBlackNode) node.getRight());
}
}
// value not in tree
return null;
}
public void insert(int value) {
// Case 1
if (root == null) {
root = new RedBlackNode(BLACK);
root.setValue(value);
// insert fake leaves
root.setRight(new RedBlackNode(true, true));
root.setLeft(new RedBlackNode(true, true));
return;
}
// insert node as red
RedBlackNode tmp = findParent(value);
RedBlackNode child = new RedBlackNode(RED);
child.setValue(value);
child.setParent(tmp);
if (value < tmp.getValue()) {
tmp.setLeft(child);
} else {
tmp.setRight(child);
}
// insert fake leaves
child.setRight(new RedBlackNode(true, true));
child.setLeft(new RedBlackNode(true, true));
RedBlackNode x = child;
while ((x != root) && (((RedBlackNode) x.getParent()).getColor() == RED)) {
if (x.getParent().isLeft()) {
RedBlackNode gParent = grandparent(x);
RedBlackNode uncle = (RedBlackNode) gParent.getRight();
if (uncle.getColor() == RED) {
((RedBlackNode) child.getParent()).setBlack();
uncle.setBlack();
gParent.setRed();
x = gParent; // move x up the tree
} else {
if (x.isRight()) {
// move x up and rotate
x = (RedBlackNode) x.getParent();
rotate_left(x);
}
((RedBlackNode) x.getParent()).setBlack();
grandparent(x).setRed();
rotate_right(grandparent(x));
}
} else { // parent is right child
RedBlackNode gParent = grandparent(x);
RedBlackNode uncle = (RedBlackNode) gParent.getLeft();
if (uncle.getColor() == RED) {
((RedBlackNode) child.getParent()).setBlack();
uncle.setBlack();
gParent.setRed();
x = gParent; // move x up the tree
} else {
if (x.isLeft()) {
// move x up and rotate
x = (RedBlackNode) x.getParent();
rotate_right(x);
}
((RedBlackNode) x.getParent()).setBlack();
grandparent(x).setRed();
rotate_left(grandparent(x));
}
}
}
root.setBlack();
}
private RedBlackNode grandparent(RedBlackNode n) {
if ((n != null) && (n.getParent() != null)) return (RedBlackNode) n.getParent().getParent();
else return null;
}
private void rotate_left(RedBlackNode x) {
RedBlackNode y = (RedBlackNode) x.getRight();
x.setRight(y.getLeft());
if (!((RedBlackNode) y.getLeft()).isFake()) {
y.getLeft().setParent(x);
}
y.setParent(x.getParent());
if (x.getParent() == null) root = y;
else {
if (x.isLeft()) {
x.getParent().setLeft(y);
} else x.getParent().setRight(y);
}
y.setLeft(x);
x.setParent(y);
}