fix(rotations): use built-in root adjustment
• remove unnecessary parameters to helper functions • use built-in root adjustment of the rotate functions • swap parameters of the rotation functions, to pass the tree first Signed-off-by: Matej Focko <mfocko@redhat.com>
This commit is contained in:
parent
2bc43652d0
commit
5388f21f04
GPG key ID:
7C47D46246790496
4 changed files with 22 additions and 66 deletions
55
avl.js
55
avl.js
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@ -33,30 +33,24 @@ class AVLTree extends RankedTree {
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);
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}
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fix0Child(x, y, z, rotatingAroundRoot, rotateLeft, rotateRight) {
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fix0Child(x, y, z, rotateLeft, rotateRight) {
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let newRoot = x.parent;
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if (!y || nodeDifference(y) == 2) {
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newRoot = rotateRight(z);
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if (rotatingAroundRoot) {
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this.root = newRoot;
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}
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newRoot = rotateRight(this, z);
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this.record("Fixing 0-child by single rotation: by z", z, newRoot);
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z.demote();
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this.record("Fixing 0-child by single rotation: demoting z", z);
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} else if (nodeDifference(y) == 1) {
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let intermediateRoot = rotateLeft(x);
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let intermediateRoot = rotateLeft(this, x);
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this.record(
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"Fixing 0-child by double-rotation: first rotation by x",
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x,
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intermediateRoot
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);
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newRoot = rotateRight(z);
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if (rotatingAroundRoot) {
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this.root = newRoot;
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}
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newRoot = rotateRight(this, z);
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this.record(
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"Fixing 0-child by double-rotation: second rotation by z",
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z,
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@ -91,8 +85,6 @@ class AVLTree extends RankedTree {
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return;
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}
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let rotatingAroundRoot = x.parent.parent == null;
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let rankDifference = nodeDifference(x);
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if (rankDifference != 0) {
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return;
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@ -101,49 +93,32 @@ class AVLTree extends RankedTree {
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let xParent = x.parent;
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if (rankDifference == 0 && x.parent.left === x) {
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this.fix0Child(
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x,
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x.right,
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xParent,
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rotatingAroundRoot,
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rotateLeft,
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rotateRight
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);
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this.fix0Child(x, x.right, xParent, rotateLeft, rotateRight);
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} else if (rankDifference == 0 && x.parent.right === x) {
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this.fix0Child(
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x,
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x.left,
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xParent,
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rotatingAroundRoot,
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rotateRight,
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rotateLeft
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);
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this.fix0Child(x, x.left, xParent, rotateRight, rotateLeft);
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}
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}
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deleteRotate(x, y, leaning, rotatingAroundRoot, rotateLeft, rotateRight) {
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deleteRotate(x, y, leaning, rotateLeft, rotateRight) {
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let newRoot = x;
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let factor = balanceFactor(y);
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switch (factor) {
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case 0:
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case leaning:
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newRoot = rotateLeft(x);
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newRoot = rotateLeft(this, x);
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break;
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default:
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let intermediateRoot = rotateRight(y);
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let intermediateRoot = rotateRight(this, y);
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this.record(
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"AVL deletion, fixing by double-rotation: by y",
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y,
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intermediateRoot
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);
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newRoot = rotateLeft(x);
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newRoot = rotateLeft(this, x);
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break;
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}
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if (rotatingAroundRoot) {
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this.root = newRoot;
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}
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this.record("AVL deletion, fixing by rotation by x", x, newRoot);
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[newRoot.left, newRoot.right, newRoot]
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@ -172,7 +147,6 @@ class AVLTree extends RankedTree {
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return false;
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}
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let rotatingAroundRoot = x.parent == null;
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let [z, leaning, toLeft, toRight] = [
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x.left,
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-1,
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@ -188,14 +162,7 @@ class AVLTree extends RankedTree {
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];
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}
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return this.deleteRotate(
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x,
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z,
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leaning,
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rotatingAroundRoot,
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toLeft,
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toRight
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);
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return this.deleteRotate(x, z, leaning, toLeft, toRight);
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}
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deleteRebalance(node, parent) {
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4
node.js
4
node.js
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@ -36,7 +36,7 @@ function nodeDifferences(node) {
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return [r - nodeRank(left), r - nodeRank(right)];
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}
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function rotateRight(x, t) {
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function rotateRight(t, x) {
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let parent = x.parent;
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let y = x.left;
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// let z = x.right;
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@ -63,7 +63,7 @@ function rotateRight(x, t) {
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return y;
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}
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function rotateLeft(x, t) {
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function rotateLeft(t, x) {
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let parent = x.parent;
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// let y = x.left;
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let z = x.right;
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10
rbt.js
10
rbt.js
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@ -47,13 +47,13 @@ class RBTree extends RankedTree {
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// ======
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// z’s uncle y is black and z is a right child
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z = p;
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rotateLeft(p, this);
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rotateLeft(this, p);
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this.record("Insertion case #2: rotating by parent");
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} else {
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// Case 3
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// ======
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// z’s uncle y is black and z is a left child
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rotateRight(pp, this);
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rotateRight(this, pp);
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this.record("Insertion case #3: rotating by grandparent");
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}
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@ -89,7 +89,7 @@ class RBTree extends RankedTree {
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// Case 1
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// ======
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// x’s sibling w is red
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rotateLeft(parent, this);
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rotateLeft(this, parent);
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this.record("Deletion case #1: rotating by parent", parent);
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w = right(parent);
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}
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@ -107,7 +107,7 @@ class RBTree extends RankedTree {
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// x’s sibling w is black,
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// w’s left child is red, and w’s right child is black
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if (nodeDifference(right(w), w) == BLACK) {
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rotateRight(w, this);
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rotateRight(this, w);
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this.record("Deletion case #3: rotating by w", w);
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w = right(parent);
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}
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@ -122,7 +122,7 @@ class RBTree extends RankedTree {
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);
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w.rank++;
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this.record("Deletion case #4: coloring w's child", w);
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rotateLeft(parent, this);
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rotateLeft(this, parent);
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this.record("Deletion case #4: rotating by parent", parent);
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x = this.root;
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19
wavl.js
19
wavl.js
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@ -21,7 +21,7 @@ class WAVLTree extends AVLTree {
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);
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}
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fixDelete(x, y, z, reversed, rotatingAroundRoot, rotateLeft, rotateRight) {
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fixDelete(x, y, z, reversed, rotateLeft, rotateRight) {
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let newRoot = x;
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let [v, w] = [y.left, y.right];
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@ -30,13 +30,9 @@ class WAVLTree extends AVLTree {
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}
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let wDiff = nodeDifference(w, y);
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if (wDiff == 1 && y.parent) {
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let oldRoot = y.parent;
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newRoot = rotateLeft(y.parent);
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if (rotatingAroundRoot) {
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this.root = newRoot;
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}
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newRoot = rotateLeft(this, y.parent);
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this.record(
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"Final step of deletion rebalance: single rotation by parent of y",
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oldRoot,
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@ -58,7 +54,7 @@ class WAVLTree extends AVLTree {
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}
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} else if (wDiff == 2 && v && v.parent) {
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let oldRoot = v.parent;
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let intermediateRoot = rotateRight(v.parent);
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let intermediateRoot = rotateRight(this, v.parent);
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this.record(
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"Final step of deletion rebalance: first of double rotation by parent of v",
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oldRoot,
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@ -66,10 +62,7 @@ class WAVLTree extends AVLTree {
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);
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oldRoot = v.parent;
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newRoot = rotateLeft(v.parent);
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if (rotatingAroundRoot) {
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this.root = newRoot;
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}
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newRoot = rotateLeft(this, v.parent);
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this.record(
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"Final step of deletion rebalance: second of double rotation by parent of v",
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oldRoot,
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@ -132,8 +125,6 @@ class WAVLTree extends AVLTree {
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return;
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}
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let rotatingAroundRoot = parent.parent == null;
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let parentNodeDiffs = nodeDifferences(parent);
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if (parentNodeDiffs.sort().equals([1, 3])) {
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if (parent.left === x) {
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@ -142,7 +133,6 @@ class WAVLTree extends AVLTree {
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parent.right,
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parent,
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false,
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rotatingAroundRoot,
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rotateLeft,
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rotateRight
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);
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@ -152,7 +142,6 @@ class WAVLTree extends AVLTree {
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parent.left,
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parent,
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true,
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rotatingAroundRoot,
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rotateRight,
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rotateLeft
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);
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