protected NODE delete(NODE node, K key) {
if (node == null) {
// We've reached a leaf. Nothing to delete.
return null;
}
int cmp = key.compareTo(node.key);
if (cmp < 0) {
// Key is less than the node. Delete in the left subtree.
node.left = delete(node.left, key);
node.size = size(node.left) + size(node.right) + 1;
return node;
} else if (cmp > 0) {
// Key is greater than the node. Delete in the right subtree.
node.right = delete(node.right, key);
node.size = size(node.left) + size(node.right) + 1;
return node;
} else {
// Delete the node.
if (node.left == null) {
// Replace node with its right subtree.
return node.right;
} else if (node.right == null) {
// Replace node with its left subtree.
return node.left;
} else if (node.right.left == null) {
// Replace node with its right subtree.
// Move the left subtree to the right node.
node.right.left = node.left;
node.right.size += size(node.left);
return node.right;
} else {
// Replace node with its successor (Hibbard).
NODE s = min(node.right);
NODE x = delete(node, s.key);
node.key = s.key;
node.value = s.value;
return x;
}
}
}
protected NODE put(NODE node, K key, V value) {
if (node == null) {
// We've reached a leaf. Create a new node to store the new value.
return createNode(key, value);
}
int cmp = key.compareTo(node.key);
if (cmp < 0) {
// Key is less than the node. Update the left subtree.
node.left = put(node.left, key, value);
node.size = size(node.left) + size(node.right) + 1;
return node;
} else if (cmp > 0) {
// Key is greater than the node. Update the right subtree.
node.right = put(node.right, key, value);
node.size = size(node.left) + size(node.right) + 1;
return node;
} else {
// Update the value on the node.
node.value = value;
return node;
}
}
