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1 颜色翻转和右旋
1.1 颜色翻转(flipcolors)
RBTree.java
package tree;
public class RBTree<K extends Comparable<K>, V> {
private static final boolean RED = true;
private static final boolean BLACK = false;
private class Node {
public K key;
public V value;
public Node left, right;
public boolean color;
public Node(K key, V value) {
this.key = key;
this.value = value;
left = null;
right = null;
color = RED;
}
}
private Node root;
private int size;
public RBTree() {
root = null;
size = 0;
}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
private boolean isRed(Node node) {
if (node == null) {
return BLACK;
}
return node.color;
}
public void add(K key, V value) {
root = add(root, key, value);
}
/*
* 向以 node 为根的二分搜索树中插入元素(key,value)
* 返回插入新节点后二分搜索树的根
* */
private Node add(Node node, K key, V value) {
if (node == null) {
size++;
return new Node(key, value);
}
if (key.compareTo(node.key) < 0) {
node.left = add(node.left, key, value);
} else if (key.compareTo(node.key) > 0) {
node.right = add(node.right,key,value);
}else{
node.value = value;
}
return node;
}
// 颜色翻转
private void flipColors(Node node){
node.color = RED;
node.left.color = BLACK;
node.right.color = BLACK;
}
}
1.2 右旋
node.left = T1
x.right = node
x.color = node.color
node.color = RED
// node x
// / \ / \
// x T2 y node
// / \ / \
// y T1 T1 T2
private Node rightRotate(Node node) {
Node x = node.left;
// 右旋转
node.left = x.right;
x.right = node;
x.color = node.color;
node.color = RED;
return x;
}