LeetCode 146 Java 版本题解及资料汇编。
题目
146. LRU 缓存 - 力扣（LeetCode）
LRU Cache - LeetCode
思路
哈希表 + 双向链表。
题解
题解1 基于 Java HashMap
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| class LRUCache {
Node head = new Node();
Node tail = new Node();
HashMap<Integer, Node> map = new HashMap<>();
int capacity;
public LRUCache(int capacity) {
this.capacity = capacity;
head.next = tail;
tail.prev = head;
}
public int get(int key) {
Node node = map.get(key);
if (node == null) {
return -1;
} else {
if (node.next != tail) {
moveToTail(node);
}
return node.value;
}
}
public void put(int key, int value) {
Node node = map.get(key);
if (node != null) {
node.value = value;
if (node.next != tail) {
moveToTail(node);
}
} else {
if (map.size() >= capacity) {
removeHead();
putInternal(key, value);
} else {
putInternal(key, value);
}
}
}
private void putInternal(int key, int value) {
Node node = new Node(key, value);
addNodeToTail(node);
map.put(key, node);
}
private void moveToTail(Node node) {
removeNode(node);
addNodeToTail(node);
}
private void removeNode(Node node) {
node.prev.next = node.next;
node.next.prev = node.prev;
node.prev = null;
node.next = null;
}
private void addNodeToTail(Node node) {
node.prev = tail.prev;
node.prev.next = node;
node.next = tail;
tail.prev = node;
}
private void removeHead() {
Node firstNode = head.next;
removeNode(head.next);
map.remove(firstNode.key);
}
private class Node {
private Node prev;
private Node next;
private int key;
private int value;
Node() {
}
Node(int key, int value) {
this.key = key;
this.value = value;
}
}
}
|
参考资料
- 官方题解：146. LRU 缓存 - 力扣（LeetCode）
- Labuladong题解：146. LRU 缓存 - 力扣（LeetCode）