public class LRU {
static HashMap<Integer, Node> map = new HashMap<>();
static Node head = new Node();
static Node end = null;
static int capacity = 4;
public static void tranverse() { // 遍历链表
Node phead = ;
while (phead != null) {
("(" + + "," + + ")->");
phead = ;
}
();
}
public static int get(int key) {
if ((key)) {
Node node = (key);
remove(node);
setHead(node); // 访问结点时，将其置为头结点
return ;
}
return -1;
}
public static void remove(Node node) {
if (null == ) {
= null;
} else {
= ;
= ;
}
}
public static void setHead(Node node) {
if ( != null) {
= ;
= node;
= node;
= head;
} else {
= node;
= head;
}
}
public static void put(int key, int value) {
if ((key)) {
Node old = (key);
= value;
remove(old);
setHead(old);
} else {
Node newCode = new Node(key, value);
(key, newCode);
if ( != null) { // 找到end所在结点
end = ;
while ( != null) {
end = ;
}
}
if (() > capacity) // 当size >= capacity时移除end结点
if ( != -1) {
();
remove(end);
setHead(newCode);
} else {
setHead(newCode);
}
} else {
setHead(newCode);
}
}
}
}
class Node { // 双向链表
int key = -1;
int value = -1;
Node pre = null;
Node next = null;
public Node() {
}
public Node(int key, int value) {
this.key = key;
this.value = value;
}
}