红黑树

1. 构造

三个属性：  排序器  根节点  个数

private final Comparator<? super K> comparator;

private transient Entry<K,V> root;

/**
 * The number of entries in the tree
 */
private transient int size = 0;

2. 插入/查询

插入

a. 计算 t

if (cpr != null) {
    do {
        parent = t;
        cmp = cpr.compare(key, t.key);
        if (cmp < 0)
            t = t.left;
        else if (cmp > 0)
            t = t.right;
        else
            return t.setValue(value);                    //层层比较  如果要插入的key和根节点的key相等 则替换值
    } while (t != null);
}

b. 插入节点

Entry<K,V> e = new Entry<>(key, value, parent);         //构建要插入的节点
if (cmp < 0)
    parent.left = e;
else
    parent.right = e;

查询

Entry<K,V> p = root;
while (p != null) {
    int cmp = k.compareTo(p.key);
    if (cmp < 0)
        p = p.left;
    else if (cmp > 0)
        p = p.right;
    else
        return p;
}

3. 左/右旋

if (parentOf(x) == leftOf(parentOf(parentOf(x)))) {
    Entry<K,V> y = rightOf(parentOf(parentOf(x)));
    if (colorOf(y) == RED) {
        setColor(parentOf(x), BLACK);
        setColor(y, BLACK);
        setColor(parentOf(parentOf(x)), RED);
        x = parentOf(parentOf(x));
    } else {
        if (x == rightOf(parentOf(x))) {
            x = parentOf(x);
            rotateLeft(x);
        }
        setColor(parentOf(x), BLACK);
        setColor(parentOf(parentOf(x)), RED);
        rotateRight(parentOf(parentOf(x)));
    }