数据结构与算法笔记目录： 《恋上数据结构》 笔记目录想加深 Java 基础推荐看这个： Java 强化笔记目录
映射的特点：
- Map 在有些编程语言中也叫做字典（dictionary，比如 Python）
- Map 中的每一个 Key 是唯一的
- Map 中的每一个 Key 对应一个 Value
类似 Set，Map 可以直接利用之前学习的链表、二叉搜索树（AVL树、红黑树）等数据结构来实现。
Map的接口定义 Map.java
public interface Map<K, V> {
int size();
boolean isEmpty();
void clear();
V put(K key, V value);
V get(K key);
V remove(K key);
boolean containsKey(K key);
boolean containsValue(V value);
void traversal(Visitor<K, V> visitor);
public static abstract class Visitor<K, V> {
boolean stop;
public abstract boolean visit(K key, V value);
}
}红黑树 RBTree 实现 TreeMap
通过 RBTree 实现的 TreeMap。
/**
* 直接由红黑树实现的映射
*/
public class TreeMap<K, V> implements Map<K, V> {
private static final boolean RED = false;
private static final boolean BLACK = true;
private int size;
private Node<K, V> root;
private Comparator<K> comparator;
public TreeMap() {
this(null);
}
public TreeMap(Comparator<K> comparator) {
this.comparator = comparator;
}
/**
* 存放 key 和 value 的红黑树节点类
*/
private static class Node<K, V> {
K key;
V value;
boolean color = RED;
Node<K, V> left;
Node<K, V> right;
Node<K, V> parent;
public Node(K key, V value, Node<K, V> parent) {
this.key = key;
this.value = value;
this.parent = parent;
}
public boolean isLeaf() { // 是否为叶子结点
return left == null && right == null;
}
public boolean hasTwoChildren() { // 是否有两个子节点
return left != null && right != null;
}
public boolean isLeftChild() { // 是否为左节点
return parent != null && this == parent.left;
}
public boolean isRightChild() { // 是否为右节点
return parent != null && this == parent.right;
}
public Node<K, V> sibling() { // 返回兄弟节点
if (isLeftChild()) {
return parent.right;
}
if (isRightChild()) {
return parent.left;
}
return null;
}
}
public int size() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public void clear() {
root = null;
size = 0;
}
public V put(K key, V value) {
KeyNotNullCheck(key); // 传入元素不能为空
// 添加第一个节点
if (root == null) {
root = new Node<>(key, value, null);
size++;
// 新添加节点之后的处理
// BST中无需处理，为 AVL树 和 B树提供可覆盖的方法
afterPut(root);
return null;
}
// 添加的不是第一个节点
// 找到父节点
Node<K, V> parent = root;
Node<K, V> node = root;
int cmp = 0;
do {
cmp = compare(key, node.key);
parent = node;
if (cmp > 0) {
node = node.right;
} else if (cmp < 0) {
node = node.left;
} else { // 相等
// 相等时的操作按需求来定，这里选择了覆盖
node.key = key;
V oldValue = node.value;
node.value = value;
return oldValue;
}
} while (node != null);
// 通过上面的while循环找到了要插入节点的父节点
// 看看插入到父节点的哪个位置
Node<K, V> newNode = new Node(key, value, parent);
if (cmp > 0) {
parent.right = newNode;
} else {
parent.left = newNode;
}
size++;
// 新添加节点之后的处理
// BST中无需处理，为 AVL树 和 B树提供可覆盖的方法
afterPut(newNode);
return null;
}
public V get(K key) {
Node<K, V> node = node(key);
return node != null ? node.value : null;
}
public V remove(K key) {
return remove(node(key));
}
private V remove(Node<K, V> node) {
if (node == null) return null;
Node<K, V> oldNode = node;
size--;
if (node.hasTwoChildren()) { // 度为2的节点
// 找到后继节点
Node<K, V> s = successor(node);
// 用后继节点的值覆盖度为2的节点的值
node.key = s.key;
node.value = s.value;
// 删除后继节点
// 这里是因为后面必然会删除node节点
// 所以直接将后继节点赋给node,在后面将它删除
node = s;
}
// 删除node节点（node的度必然是1或者0）
Node<K, V> replacement = node.left != null ? node.left : node.right;
if (replacement != null) { // node是度为1的节点
// 核心：用子节点替代原节点的位置
// 更改parent
replacement.parent = node.parent;
// 更改parent的left、right的指向
if (node.parent == null) { // node是度为1的节点并且是根节点
root = replacement;
} else if (node == node.parent.left) {
node.parent.left = replacement;
} else { // node == node.parent.right
node.parent.right = replacement;
}
// 删除节点之后的处理，BST中无需处理，为 AVL树 和 B树提供可覆盖的方法
afterRemove(replacement);
} else if (node.parent == null) { // node是叶子节点并且是根节点
root = null;
// 删除节点之后的处理，BST中无需处理，为 AVL树 和 B树提供可覆盖的方法
afterRemove(node);
} else { // node是叶子节点，但不是根节点
if (node == node.parent.left) { // 是左子树
node.parent.left = null;
} else { // node == node.parent.right // 是右子树
node.parent.right = null;
}
// 删除节点之后的处理，BST中无需处理，为 AVL树 和 B树提供可覆盖的方法
afterRemove(node);
}
return oldNode.value;
}
public boolean containsKey(K key) {
return node(key) != null;
}
public boolean containsValue(V value) {
if(root == null) return false;
Queue<Node<K, V>> queue = new LinkedList<>();
queue.offer(root);
while(!queue.isEmpty()){
Node<K, V> node = queue.poll();
if(valEquals(value, node.value)) return true;
if(node.left != null){
queue.offer(node.left);
}
if(node.right != null){
queue.offer(node.right);
}
}
return false;
}
public void traversal(Visitor<K, V> visitor) {
if (visitor == null) return;
traversal(root, visitor);
}
public void traversal(Node<K, V> node, Visitor<K, V> visitor){
if(node == null || visitor.stop) return;
traversal(node.left, visitor);
if(visitor.stop) return;
visitor.visit(node.key, node.value);
traversal(node.right, visitor);
}
private boolean valEquals(V v1, V v2) {
return v1 == null ? v2 == null : v1.equals(v2);
}
protected Node<K, V> predecessor(Node<K, V> node) {
if (node == null) return null;
// 前驱节点在左子树当中（left.right.right.right....）
Node<K, V> p = node.left;
if (p != null) {
while (p.right != null) {
p = p.right;
}
return p;
}
// 从父节点、祖父节点中寻找前驱节点
while (node.parent != null && node == node.parent.left) {
node = node.parent;
}
// node.parent == null
// node == node.parent.right
return node.parent;
}
protected Node<K, V> successor(Node<K, V> node) {
if (node == null) return null;
// 前驱节点在左子树当中（right.left.left.left....）
Node<K, V> p = node.right;
if (p != null) {
while (p.left != null) {
p = p.left;
}
return p;
}
// 从父节点、祖父节点中寻找前驱节点
while (node.parent != null && node == node.parent.right) {
node = node.parent;
}
return node.parent;
}
private Node<K, V> node(K key) {
Node<K, V> node = root;
while (node != null) {
int cmp = compare(key, node.key);
if (cmp == 0) return node;
if (cmp > 0) {
node = node.right;
} else { // cmp < 0
node = node.left;
}
}
return null;
}
private void afterRemove(Node<K, V> node) {
// 如果删除的节点是红色
// 或者 用以取代删除节点的子节点是红色
if (isRed(node)) {
black(node);
return;
}
Node<K, V> parent = node.parent;
// 删除的是根节点
if (parent == null) return;
// 删除的是黑色叶子节点【下溢】
// 判断被删除的node是左还是右
boolean left = parent.left == null || node.isLeftChild();
Node<K, V> sibling = left ? parent.right : parent.left;
if (left) { // 被删除的节点在左边，兄弟节点在右边
if (isRed(sibling)) { // 兄弟节点是红色
black(sibling);
red(parent);
rotateLeft(parent);
// 更换兄弟
sibling = parent.right;
}
// 兄弟节点必然是黑色
if (isBlack(sibling.left) && isBlack(sibling.right)) {
// 兄弟节点没有1个红色子节点，父节点要向下跟兄弟节点合并
boolean parentBlack = isBlack(parent);
black(parent);
red(sibling);
if (parentBlack) {
afterRemove(parent);
}
} else { // 兄弟节点至少有1个红色子节点，向兄弟节点借元素
// 兄弟节点的左边是黑色，兄弟要先旋转
if (isBlack(sibling.right)) {
rotateRight(sibling);
sibling = parent.right;
}
color(sibling, colorOf(parent));
black(sibling.right);
black(parent);
rotateLeft(parent);
}
} else { // 被删除的节点在右边，兄弟节点在左边
if (isRed(sibling)) { // 兄弟节点是红色
black(sibling);
red(parent);
rotateRight(parent);
// 更换兄弟
sibling = parent.left;
}
// 兄弟节点必然是黑色
if (isBlack(sibling.left) && isBlack(sibling.right)) {
// 兄弟节点没有1个红色子节点，父节点要向下跟兄弟节点合并
boolean parentBlack = isBlack(parent);
black(parent);
red(sibling);
if (parentBlack) {
afterRemove(parent);
}
} else { // 兄弟节点至少有1个红色子节点，向兄弟节点借元素
// 兄弟节点的左边是黑色，兄弟要先旋转
if (isBlack(sibling.left)) {
rotateLeft(sibling);
sibling = parent.left;
}
color(sibling, colorOf(parent));
black(sibling.left);
black(parent);
rotateRight(parent);
}
}
}
private void afterPut(Node<K, V> node){
Node<K, V> parent = node.parent;
// 添加的是根节点 或者 上溢到达了根节点
if (parent == null) {
black(node);
return;
}
// 如果父节点是黑色，直接返回
if (isBlack(parent)) return;
// 叔父节点
Node<K, V> uncle = parent.sibling();
// 祖父节点
Node<K, V> grand = red(parent.parent);
if (isRed(uncle)) { // 叔父节点是红色【B树节点上溢】
black(parent);
black(uncle);
// 把祖父节点当做是新添加的节点
afterPut(grand);
return;
}
// 叔父节点不是红色
if (parent.isLeftChild()) { // L
if (node.isLeftChild()) { // LL
black(parent);
} else { // LR
black(node);
rotateLeft(parent);
}
rotateRight(grand);
} else { // R
if (node.isLeftChild()) { // RL
black(node);
rotateRight(parent);
} else { // RR
black(parent);
}
rotateLeft(grand);
}
}
private void rotateLeft(Node<K, V> grand) {
Node<K, V> parent = grand.right;
Node<K, V> child = parent.left;
grand.right = child;
parent.left = grand;
afterRotate(grand, parent, child);
}
private void rotateRight(Node<K, V> grand) {
Node<K, V> parent = grand.left;
Node<K, V> child = parent.right;
grand.left = child;
parent.right = grand;
afterRotate(grand, parent, child);
}
private void afterRotate(Node<K, V> grand, Node<K, V> parent, Node<K, V> child) {
// 让parent称为子树的根节点
parent.parent = grand.parent;
if (grand.isLeftChild()) {
grand.parent.left = parent;
} else if (grand.isRightChild()) {
grand.parent.right = parent;
} else { // grand是root节点
root = parent;
}
// 更新child的parent
if (child != null) {
child.parent = grand;
}
// 更新grand的parent
grand.parent = parent;
}
private Node<K, V> color(Node<K, V> node, boolean color) {
if (node == null) return node;
node.color = color;
return node;
}
private Node<K, V> red(Node<K, V> node) {
return color(node, RED);
}
private Node<K, V> black(Node<K, V> node) {
return color(node, BLACK);
}
private boolean colorOf(Node<K, V> node) {
return node == null ? BLACK : node.color;
}
private boolean isBlack(Node<K, V> node) {
return colorOf(node) == BLACK;
}
private boolean isRed(Node<K, V> node) {
return colorOf(node) == RED;
}
private int compare(K k1, K k2) {
if (comparator != null) {
return comparator.compare(k1, k2);
}
return ((Comparable<K>)k1).compareTo(k2);
}
private void KeyNotNullCheck(K key) {
if (key == null) {
throw new IllegalArgumentException("key must not be null");
}
}
}
TreeMap 分析
时间复杂度（平均）
- 添加、删除、搜索：O(logn)
特点
- Key 必须具备可比较性
- 元素的分布是有顺序的
在实际应用中，很多时候的需求
- Map 中存储的元素不需要讲究顺序
- Map 中的 Key 不需要具备可比较性
不考虑顺序、不考虑 Key 的可比较性，Map 有更好的实现方案，平均时间复杂度可以达到 O(1)
- 那就是采取 哈希表 来实现 Map
哈希表实现 HashMap
通过哈希表实现 HashMap
@SuppressWarnings({"unchecked", "rawtypes"})
public class HashMap<K, V> implements Map<K, V> {
private static final boolean RED = false;
private static final boolean BLACK = true;
private int size;
private Node<K, V>[] table;
private static final int DEFAULT_CAPACITY = 1 << 4;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
public HashMap() {
table = new Node[DEFAULT_CAPACITY];
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
public void clear() {
if (size == 0) return;
size = 0;
for (int i = 0; i < table.length; i++) {
table[i] = null;
}
}
@Override
public V put(K key, V value) {
resize();
int index = index(key);
// 取出index位置的红黑树根节点
Node<K, V> root = table[index];
if (root == null) {
root = createNode(key, value, null);
table[index] = root;
size++;
fixAfterPut(root);
return null;
}
// 添加新的节点到红黑树上面
Node<K, V> parent = root;
Node<K, V> node = root;
int cmp = 0;
K k1 = key;
int h1 = hash(k1);
Node<K, V> result = null;
boolean searched = false; // 是否已经搜索过这个key
do {
parent = node;
K k2 = node.key;
int h2 = node.hash;
if (h1 > h2) {
cmp = 1;
} else if (h1 < h2) {
cmp = -1;
} else if (Objects.equals(k1, k2)) {
cmp = 0;
} else if (k1 != null && k2 != null
&& k1 instanceof Comparable
&& k1.getClass() == k2.getClass()
&& (cmp = ((Comparable)k1).compareTo(k2)) != 0) {
} else if (searched) { // 已经扫描了
cmp = System.identityHashCode(k1) - System.identityHashCode(k2);
} else { // searched == false; 还没有扫描，然后再根据内存地址大小决定左右
if ((node.left != null && (result = node(node.left, k1)) != null)
|| (node.right != null && (result = node(node.right, k1)) != null)) {
// 已经存在这个key
node = result;
cmp = 0;
} else { // 不存在这个key
searched = true;
cmp = System.identityHashCode(k1) - System.identityHashCode(k2);
}
}
if (cmp > 0) {
node = node.right;
} else if (cmp < 0) {
node = node.left;
} else { // 相等
V oldValue = node.value;
node.key = key;
node.value = value;
node.hash = h1;
return oldValue;
}
} while (node != null);
// 看看插入到父节点的哪个位置
Node<K, V> newNode = createNode(key, value, parent);
if (cmp > 0) {
parent.right = newNode;
} else {
parent.left = newNode;
}
size++;
// 新添加节点之后的处理
fixAfterPut(newNode);
return null;
}
@Override
public V get(K key) {
Node<K, V> node = node(key);
return node != null ? node.value : null;
}
@Override
public V remove(K key) {
return remove(node(key));
}
@Override
public boolean containsKey(K key) {
return node(key) != null;
}
@Override
public boolean containsValue(V value) {
if (size == 0) return false;
Queue<Node<K, V>> queue = new LinkedList<>();
for (int i = 0; i < table.length; i++) {
if (table[i] == null) continue;
queue.offer(table[i]);
while (!queue.isEmpty()) {
Node<K, V> node = queue.poll();
if (Objects.equals(value, node.value)) return true;
if (node.left != null) {
queue.offer(node.left);
}
if (node.right != null) {
queue.offer(node.right);
}
}
}
return false;
}
@Override
public void traversal(Visitor<K, V> visitor) {
if (size == 0 || visitor == null) return;
Queue<Node<K, V>> queue = new LinkedList<>();
for (int i = 0; i < table.length; i++) {
if (table[i] == null) continue;
queue.offer(table[i]);
while (!queue.isEmpty()) {
Node<K, V> node = queue.poll();
if (visitor.visit(node.key, node.value)) return;
if (node.left != null) {
queue.offer(node.left);
}
if (node.right != null) {
queue.offer(node.right);
}
}
}
}
/*
public void print() {
if (size == 0) return;
for (int i = 0; i < table.length; i++) {
final Node<K, V> root = table[i];
System.out.println("【index = " + i + "】");
BinaryTrees.println(new BinaryTreeInfo() {
@Override
public Object string(Object node) {
return node;
}
@Override
public Object root() {
return root;
}
@Override
public Object right(Object node) {
return ((Node<K, V>)node).right;
}
@Override
public Object left(Object node) {
return ((Node<K, V>)node).left;
}
});
System.out.println("---------------------------------------------------");
}
}
*/
protected Node<K, V> createNode(K key, V value, Node<K, V> parent) {
return new Node<>(key, value, parent);
}
protected void afterRemove(Node<K, V> willNode, Node<K, V> removedNode) { }
private void resize() {
// 装填因子 <= 0.75
if (size / table.length <= DEFAULT_LOAD_FACTOR) return;
Node<K, V>[] oldTable = table;
table = new Node[oldTable.length << 1];
Queue<Node<K, V>> queue = new LinkedList<>();
for (int i = 0; i < oldTable.length; i++) {
if (oldTable[i] == null) continue;
queue.offer(oldTable[i]);
while (!queue.isEmpty()) {
Node<K, V> node = queue.poll();
if (node.left != null) {
queue.offer(node.left);
}
if (node.right != null) {
queue.offer(node.right);
}
// 挪动代码得放到最后面
moveNode(node);
}
}
}
private void moveNode(Node<K, V> newNode) {
// 重置
newNode.parent = null;
newNode.left = null;
newNode.right = null;
newNode.color = RED;
int index = index(newNode);
// 取出index位置的红黑树根节点
Node<K, V> root = table[index];
if (root == null) {
root = newNode;
table[index] = root;
fixAfterPut(root);
return;
}
// 添加新的节点到红黑树上面
Node<K, V> parent = root;
Node<K, V> node = root;
int cmp = 0;
K k1 = newNode.key;
int h1 = newNode.hash;
do {
parent = node;
K k2 = node.key;
int h2 = node.hash;
if (h1 > h2) {
cmp = 1;
} else if (h1 < h2) {
cmp = -1;
} else if (k1 != null && k2 != null
&& k1 instanceof Comparable
&& k1.getClass() == k2.getClass()
&& (cmp = ((Comparable)k1).compareTo(k2)) != 0) {
} else {
cmp = System.identityHashCode(k1) - System.identityHashCode(k2);
}
if (cmp > 0) {
node = node.right;
} else if (cmp < 0) {
node = node.left;
}
} while (node != null);
// 看看插入到父节点的哪个位置
newNode.parent = parent;
if (cmp > 0) {
parent.right = newNode;
} else {
parent.left = newNode;
}
// 新添加节点之后的处理
fixAfterPut(newNode);
}
protected V remove(Node<K, V> node) {
if (node == null) return null;
Node<K, V> willNode = node;
size--;
V oldValue = node.value;
if (node.hasTwoChildren()) { // 度为2的节点
// 找到后继节点
Node<K, V> s = successor(node);
// 用后继节点的值覆盖度为2的节点的值
node.key = s.key;
node.value = s.value;
node.hash = s.hash;
// 删除后继节点
node = s;
}
// 删除node节点（node的度必然是1或者0）
Node<K, V> replacement = node.left != null ? node.left : node.right;
int index = index(node);
if (replacement != null) { // node是度为1的节点
// 更改parent
replacement.parent = node.parent;
// 更改parent的left、right的指向
if (node.parent == null) { // node是度为1的节点并且是根节点
table[index] = replacement;
} else if (node == node.parent.left) {
node.parent.left = replacement;
} else { // node == node.parent.right
node.parent.right = replacement;
}
// 删除节点之后的处理
fixAfterRemove(replacement);
} else if (node.parent == null) { // node是叶子节点并且是根节点
table[index] = null;
} else { // node是叶子节点，但不是根节点
if (node == node.parent.left) {
node.parent.left = null;
} else { // node == node.parent.right
node.parent.right = null;
}
// 删除节点之后的处理
fixAfterRemove(node);
}
// 交给子类去处理
afterRemove(willNode, node);
return oldValue;
}
private Node<K, V> successor(Node<K, V> node) {
if (node == null) return null;
// 前驱节点在左子树当中（right.left.left.left....）
Node<K, V> p = node.right;
if (p != null) {
while (p.left != null) {
p = p.left;
}
return p;
}
// 从父节点、祖父节点中寻找前驱节点
while (node.parent != null && node == node.parent.right) {
node = node.parent;
}
return node.parent;
}
private Node<K, V> node(K key) {
Node<K, V> root = table[index(key)];
return root == null ? null : node(root, key);
}
private Node<K, V> node(Node<K, V> node, K k1) {
int h1 = hash(k1);
// 存储查找结果
Node<K, V> result = null;
int cmp = 0;
while (node != null) {
K k2 = node.key;
int h2 = node.hash;
// 先比较哈希值
if (h1 > h2) {
node = node.right;
} else if (h1 < h2) {
node = node.left;
} else if (Objects.equals(k1, k2)) {
return node;
} else if (k1 != null && k2 != null
&& k1 instanceof Comparable
&& k1.getClass() == k2.getClass()
&& (cmp = ((Comparable)k1).compareTo(k2)) != 0) {
node = cmp > 0 ? node.right : node.left;
} else if (node.right != null && (result = node(node.right, k1)) != null) {
return result;
} else { // 只能往左边找
node = node.left;
}
}
return null;
}
/**
* 根据key生成对应的索引（在桶数组中的位置）
*/
private int index(K key) {
return hash(key) & (table.length - 1);
}
private int hash(K key) {
if (key == null) return 0;
int hash = key.hashCode();
return hash ^ (hash >>> 16);
}
private int index(Node<K, V> node) {
return node.hash & (table.length - 1);
}
private void fixAfterRemove(Node<K, V> node) {
// 如果删除的节点是红色
// 或者 用以取代删除节点的子节点是红色
if (isRed(node)) {
black(node);
return;
}
Node<K, V> parent = node.parent;
if (parent == null) return;
// 删除的是黑色叶子节点【下溢】
// 判断被删除的node是左还是右
boolean left = parent.left == null || node.isLeftChild();
Node<K, V> sibling = left ? parent.right : parent.left;
if (left) { // 被删除的节点在左边，兄弟节点在右边
if (isRed(sibling)) { // 兄弟节点是红色
black(sibling);
red(parent);
rotateLeft(parent);
// 更换兄弟
sibling = parent.right;
}
// 兄弟节点必然是黑色
if (isBlack(sibling.left) && isBlack(sibling.right)) {
// 兄弟节点没有1个红色子节点，父节点要向下跟兄弟节点合并
boolean parentBlack = isBlack(parent);
black(parent);
red(sibling);
if (parentBlack) {
fixAfterRemove(parent);
}
} else { // 兄弟节点至少有1个红色子节点，向兄弟节点借元素
// 兄弟节点的左边是黑色，兄弟要先旋转
if (isBlack(sibling.right)) {
rotateRight(sibling);
sibling = parent.right;
}
color(sibling, colorOf(parent));
black(sibling.right);
black(parent);
rotateLeft(parent);
}
} else { // 被删除的节点在右边，兄弟节点在左边
if (isRed(sibling)) { // 兄弟节点是红色
black(sibling);
red(parent);
rotateRight(parent);
// 更换兄弟
sibling = parent.left;
}
// 兄弟节点必然是黑色
if (isBlack(sibling.left) && isBlack(sibling.right)) {
// 兄弟节点没有1个红色子节点，父节点要向下跟兄弟节点合并
boolean parentBlack = isBlack(parent);
black(parent);
red(sibling);
if (parentBlack) {
fixAfterRemove(parent);
}
} else { // 兄弟节点至少有1个红色子节点，向兄弟节点借元素
// 兄弟节点的左边是黑色，兄弟要先旋转
if (isBlack(sibling.left)) {
rotateLeft(sibling);
sibling = parent.left;
}
color(sibling, colorOf(parent));
black(sibling.left);
black(parent);
rotateRight(parent);
}
}
}
private void fixAfterPut(Node<K, V> node) {
Node<K, V> parent = node.parent;
// 添加的是根节点 或者 上溢到达了根节点
if (parent == null) {
black(node);
return;
}
// 如果父节点是黑色，直接返回
if (isBlack(parent)) return;
// 叔父节点
Node<K, V> uncle = parent.sibling();
// 祖父节点
Node<K, V> grand = red(parent.parent);
if (isRed(uncle)) { // 叔父节点是红色【B树节点上溢】
black(parent);
black(uncle);
// 把祖父节点当做是新添加的节点
fixAfterPut(grand);
return;
}
// 叔父节点不是红色
if (parent.isLeftChild()) { // L
if (node.isLeftChild()) { // LL
black(parent);
} else { // LR
black(node);
rotateLeft(parent);
}
rotateRight(grand);
} else { // R
if (node.isLeftChild()) { // RL
black(node);
rotateRight(parent);
} else { // RR
black(parent);
}
rotateLeft(grand);
}
}
private void rotateLeft(Node<K, V> grand) {
Node<K, V> parent = grand.right;
Node<K, V> child = parent.left;
grand.right = child;
parent.left = grand;
afterRotate(grand, parent, child);
}
private void rotateRight(Node<K, V> grand) {
Node<K, V> parent = grand.left;
Node<K, V> child = parent.right;
grand.left = child;
parent.right = grand;
afterRotate(grand, parent, child);
}
private void afterRotate(Node<K, V> grand, Node<K, V> parent, Node<K, V> child) {
// 让parent称为子树的根节点
parent.parent = grand.parent;
if (grand.isLeftChild()) {
grand.parent.left = parent;
} else if (grand.isRightChild()) {
grand.parent.right = parent;
} else { // grand是root节点
table[index(grand)] = parent;
}
// 更新child的parent
if (child != null) {
child.parent = grand;
}
// 更新grand的parent
grand.parent = parent;
}
private Node<K, V> color(Node<K, V> node, boolean color) {
if (node == null) return node;
node.color = color;
return node;
}
private Node<K, V> red(Node<K, V> node) {
return color(node, RED);
}
private Node<K, V> black(Node<K, V> node) {
return color(node, BLACK);
}
private boolean colorOf(Node<K, V> node) {
return node == null ? BLACK : node.color;
}
private boolean isBlack(Node<K, V> node) {
return colorOf(node) == BLACK;
}
private boolean isRed(Node<K, V> node) {
return colorOf(node) == RED;
}
protected static class Node<K, V> {
int hash;
K key;
V value;
boolean color = RED;
Node<K, V> left;
Node<K, V> right;
Node<K, V> parent;
public Node(K key, V value, Node<K, V> parent) {
this.key = key;
int hash = key == null ? 0 : key.hashCode();
this.hash = hash ^ (hash >>> 16);
this.value = value;
this.parent = parent;
}
public boolean hasTwoChildren() {
return left != null && right != null;
}
public boolean isLeftChild() {
return parent != null && this == parent.left;
}
public boolean isRightChild() {
return parent != null && this == parent.right;
}
public Node<K, V> sibling() {
if (isLeftChild()) {
return parent.right;
}
if (isRightChild()) {
return parent.left;
}
return null;
}
@Override
public String toString() {
return "Node_" + key + "_" + value;
}
}
}HashMap 升级为 LinkedHashMap
在 HashMap 的基础上维护元素的添加顺序，使得遍历的结果遵从添加顺序
@SuppressWarnings({ "rawtypes", "unchecked" })
public class LinkedHashMap<K, V> extends HashMap<K, V> {
private LinkedNode<K, V> first;
private LinkedNode<K, V> last;
@Override
public void clear() {
super.clear();
first = null;
last = null;
}
@Override
public boolean containsValue(V value) {
LinkedNode<K, V> node = first;
while (node != null) {
if (Objects.equals(value, node.value)) return true;
node = node.next;
}
return false;
}
@Override
public void traversal(Visitor<K, V> visitor) {
if (visitor == null) return;
LinkedNode<K, V> node = first;
while (node != null) {
if (visitor.visit(node.key, node.value)) return;
node = node.next;
}
}
@Override
protected void afterRemove(Node<K, V> willNode, Node<K, V> removedNode) {
LinkedNode<K, V> node1 = (LinkedNode<K, V>) willNode;
LinkedNode<K, V> node2 = (LinkedNode<K, V>) removedNode;
if (node1 != node2) {
// 交换linkedWillNode和linkedRemovedNode在链表中的位置
// 交换prev
LinkedNode<K, V> tmp = node1.prev;
node1.prev = node2.prev;
node2.prev = tmp;
if (node1.prev == null) {
first = node1;
} else {
node1.prev.next = node1;
}
if (node2.prev == null) {
first = node2;
} else {
node2.prev.next = node2;
}
// 交换next
tmp = node1.next;
node1.next = node2.next;
node2.next = tmp;
if (node1.next == null) {
last = node1;
} else {
node1.next.prev = node1;
}
if (node2.next == null) {
last = node2;
} else {
node2.next.prev = node2;
}
}
LinkedNode<K, V> prev = node2.prev;
LinkedNode<K, V> next = node2.next;
if (prev == null) {
first = next;
} else {
prev.next = next;
}
if (next == null) {
last = prev;
} else {
next.prev = prev;
}
}
@Override
protected Node<K, V> createNode(K key, V value, Node<K, V> parent) {
LinkedNode node = new LinkedNode(key, value, parent);
if (first == null) {
first = last = node;
} else {
last.next = node;
node.prev = last;
last = node;
}
return node;
}
private static class LinkedNode<K, V> extends Node<K, V> {
LinkedNode<K, V> prev;
LinkedNode<K, V> next;
public LinkedNode(K key, V value, Node<K, V> parent) {
super(key, value, parent);
}
}
}
