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| class LRUCache {
public class Node {
int key, val;
Node pre;
Node next;
public Node() {}
public Node(int _k, int _v) {
this.key = _k;
this.val = _v;
}
}
public class MyList {
Node head = new Node(0,0);
Node tail = new Node(0,0);
public MyList() {
head.next = tail;
tail.pre = head;
}
public void headInsert(Node node) {
node.next = head.next;
node.pre = head;
head.next.pre = node;
head.next = node;
}
public void remove(Node node) {
Node nodePre = node.pre;
Node nodeNext = node.next;
nodePre.next = nodeNext;
nodeNext.pre = nodePre;
}
public Node removeLast() {
Node nodeLast = tail.pre;
remove(nodeLast);
return nodeLast;
}
}
public int capacity;
public Map<Integer, Node> map;
public MyList myList;
public LRUCache(int capacity) {
this.capacity = capacity;
map = new HashMap<>();
myList = new MyList();
}
public int get(int key) {
if(!map.containsKey(key)) {
return -1;
}
Node node = map.get(key);
myList.remove(node);
myList.headInsert(node);
return node.val;
}
public void put(int key, int value) {
if(map.containsKey(key)) {
Node node = map.get(key);
node.val = value;
myList.remove(node);
myList.headInsert(node);
} else {
Node node = new Node(key, value);
if(map.size() == capacity) {
Node last = myList.removeLast();
map.remove(last.key);
}
myList.headInsert(node);
map.put(key, node);
}
}
}
|