// based on: https://algs4.cs.princeton.edu/33balanced/RedBlackBST.java.html // TODO: extends AbstractSet<Long> sclass LongTreeSet implements Iterable<Long> { // Left-leaning red-black BST with long values. // This is the 2-3 version. private static final boolean RED = true; private static final boolean BLACK = false; private Node root; // root of the BST int size; // size of tree set // BST helper node data type private sclass Node { private long val; // associated data private Node left, right; // links to left and right subtrees private bool color; // color of parent link public Node(long val, boolean color) { this.val = val; this.color = color; } } *() {} *(Cl<Long> cl) { addAll(cl); } // is node x red; false if x is null ? private boolean isRed(Node x) { if (x == null) return false; return x.color == RED; } public int size() { ret size; } public boolean isEmpty() { return root == null; } public bool add(long val) { int oldSize = size; root = put(root, val); root.color = BLACK; ifdef CompactTreeSet_debug assertTrue(check()); endifdef ret size > oldSize; } // insert the value in the subtree rooted at h private Node put(Node h, long val) { if (h == null) { ++size; ret new Node(val, RED); } int cmp = compare(val, h.val); if (cmp < 0) h.left = put(h.left, val); else if (cmp > 0) h.right = put(h.right, val); else { /*h.val = val;*/ } // no overwriting // fix-up any right-leaning links if (isRed(h.right) && !isRed(h.left)) h = rotateLeft(h); if (isRed(h.left) && isRed(h.left.left)) h = rotateRight(h); if (isRed(h.left) && isRed(h.right)) flipColors(h); ret h; } // overridable if you want custom sorting int compare(long a, long b) { ret cmp(a, b); } public bool remove(long key) { if (!contains(key)) false; // if both children of root are black, set root to red if (!isRed(root.left) && !isRed(root.right)) root.color = RED; root = delete(root, key); if (!isEmpty()) root.color = BLACK; // assert check(); true; } // delete the key-value pair with the given key rooted at h private Node delete(Node h, long key) { // assert get(h, key) != null; if (compare(key, h.val) < 0) { if (!isRed(h.left) && !isRed(h.left.left)) h = moveRedLeft(h); h.left = delete(h.left, key); } else { if (isRed(h.left)) h = rotateRight(h); if (compare(key, h.val) == 0 && (h.right == null)) { --size; null; } if (!isRed(h.right) && !isRed(h.right.left)) h = moveRedRight(h); if (compare(key, h.val) == 0) { --size; Node x = min(h.right); h.val = x.val; // h.val = get(h.right, min(h.right).val); // h.val = min(h.right).val; h.right = deleteMin(h.right); } else h.right = delete(h.right, key); } return balance(h); } // make a left-leaning link lean to the right private Node rotateRight(Node h) { // assert (h != null) && isRed(h.left); Node x = h.left; h.left = x.right; x.right = h; x.color = x.right.color; x.right.color = RED; return x; } // make a right-leaning link lean to the left private Node rotateLeft(Node h) { // assert (h != null) && isRed(h.right); Node x = h.right; h.right = x.left; x.left = h; x.color = x.left.color; x.left.color = RED; return x; } // flip the colors of a node and its two children private void flipColors(Node h) { // h must have opposite color of its two children // assert (h != null) && (h.left != null) && (h.right != null); // assert (!isRed(h) && isRed(h.left) && isRed(h.right)) // || (isRed(h) && !isRed(h.left) && !isRed(h.right)); h.color = !h.color; h.left.color = !h.left.color; h.right.color = !h.right.color; } // Assuming that h is red and both h.left and h.left.left // are black, make h.left or one of its children red. private Node moveRedLeft(Node h) { // assert (h != null); // assert isRed(h) && !isRed(h.left) && !isRed(h.left.left); flipColors(h); if (isRed(h.right.left)) { h.right = rotateRight(h.right); h = rotateLeft(h); flipColors(h); } return h; } // Assuming that h is red and both h.right and h.right.left // are black, make h.right or one of its children red. private Node moveRedRight(Node h) { // assert (h != null); // assert isRed(h) && !isRed(h.right) && !isRed(h.right.left); flipColors(h); if (isRed(h.left.left)) { h = rotateRight(h); flipColors(h); } return h; } // restore red-black tree invariant private Node balance(Node h) { // assert (h != null); if (isRed(h.right)) h = rotateLeft(h); if (isRed(h.left) && isRed(h.left.left)) h = rotateRight(h); if (isRed(h.left) && isRed(h.right)) flipColors(h); return h; } /** * Returns the height of the BST (for debugging). * @return the height of the BST (a 1-node tree has height 0) */ public int height() { return height(root); } private int height(Node x) { if (x == null) return -1; return 1 + Math.max(height(x.left), height(x.right)); } public bool contains(long val) { ret find(root, val) != null; } Node find(Node x, long key) { while (x != null) { int cmp = compare(key, x.val); if (cmp < 0) x = x.left; else if (cmp > 0) x = x.right; else ret x; } null; } private boolean check() { if (!is23()) println("Not a 2-3 tree"); if (!isBalanced()) println("Not balanced"); return is23() && isBalanced(); } // Does the tree have no red right links, and at most one (left) // red links in a row on any path? private boolean is23() { return is23(root); } private boolean is23(Node x) { if (x == null) return true; if (isRed(x.right)) return false; if (x != root && isRed(x) && isRed(x.left)) return false; return is23(x.left) && is23(x.right); } // do all paths from root to leaf have same number of black edges? private boolean isBalanced() { int black = 0; // number of black links on path from root to min Node x = root; while (x != null) { if (!isRed(x)) black++; x = x.left; } return isBalanced(root, black); } // does every path from the root to a leaf have the given number of black links? private boolean isBalanced(Node x, int black) { if (x == null) return black == 0; if (!isRed(x)) black--; return isBalanced(x.left, black) && isBalanced(x.right, black); } public void clear() { root = null; size = 0; } // the smallest key in subtree rooted at x; null if no such key private Node min(Node x) { // assert x != null; while (x.left != null) x = x.left; ret x; } private Node deleteMin(Node h) { if (h.left == null) return null; if (!isRed(h.left) && !isRed(h.left.left)) h = moveRedLeft(h); h.left = deleteMin(h.left); ret balance(h); } public Iterator<Long> iterator() { ret new MyIterator; } class MyIterator extends ItIt<Long> { new L<Node> path; *() { fetch(root); } void fetch(Node node) { while (node != null) { path.add(node); node = node.left; } } public bool hasNext() { ret !path.isEmpty(); } public Long next() { if (path.isEmpty()) fail("no more elements"); Node node = popLast(path); // last node is always a leaf, so left is null // so proceed to fetch right branch fetch(node.right); ret node.val; } } // Returns the smallest key in the symbol table greater than or equal to {@code key}. public Long ceiling(long key) { Node x = ceiling(root, key); ret x == null ? null : x.val; } // the smallest key in the subtree rooted at x greater than or equal to the given key Node ceiling(Node x, long key) { if (x == null) null; int cmp = compare(key, x.val); if (cmp == 0) ret x; if (cmp > 0) ret ceiling(x.right, key); Node t = ceiling(x.left, key); if (t != null) ret t; else ret x; } public Long floor(long key) { Node x = floor(root, key); ret x == null ? null : x.val; } // the largest key in the subtree rooted at x less than or equal to the given key Node floor(Node x, long key) { if (x == null) null; int cmp = compare(key, x.val); if (cmp == 0) ret x; if (cmp < 0) ret floor(x.left, key); Node t = floor(x.right, key); if (t != null) ret t; else ret x; } void addAll(Cl<Long> l) { fOr (long x : l) add(x); } }
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Snippet ID: | #1030407 |
Snippet name: | LongTreeSet [backup before AbstractSet] |
Eternal ID of this version: | #1030407/1 |
Text MD5: | f9599b5fe7e6c073d04fca39170136c9 |
Author: | stefan |
Category: | javax |
Type: | JavaX fragment (include) |
Public (visible to everyone): | Yes |
Archived (hidden from active list): | No |
Created/modified: | 2020-12-13 17:19:14 |
Source code size: | 9465 bytes / 335 lines |
Pitched / IR pitched: | No / No |
Views / Downloads: | 170 / 192 |
Referenced in: | -