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import java.util.HashMap;

/*

* LRU Cache

* Design and implement a data structure for Least Recently Used (LRU) cache.

* It should support the following operations: get and set.

* get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.

* set(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.

*/

public class Solution48 {

/*Time Limit Exceeded

private int capacity;

private HashMap<Integer, Integer> map;

private HashMap<Integer, Integer> gets;

public Solution48(int capacity) {

this.capacity = capacity;

map = new HashMap<Integer, Integer>();

gets = new HashMap<Integer, Integer>();

}

public int get(int key) {

if (map.containsKey(key)) {

int temp = gets.get(key);

gets.remove(key);

gets.put(key, ++temp);

return map.get(key);

}

return -1;

}

public void set(int key, int value) {

if (map.containsKey(key)) {

map.remove(key);

map.put(key, value);

} else {

if (capacity > 0) {

map.put(key, value);

gets.put(key, 0);

capacity--;

} else {

int min = 0;

int k = 0;

Iterator<Entry<Integer, Integer>> iter = map.entrySet().iterator() ;

while (iter.hasNext()) {

Map.Entry<Integer, Integer> entry = iter.next();

k = (min > entry.getValue() ? entry.getKey() : k);

min = (min > entry.getValue() ? entry.getValue() : min);

}

map.remove(k);

gets.remove(k);

map.put(key, value);

gets.put(key, 0);

}

}

}*/

static class Node {

int key;

int value;

Node prev;

Node next;

Node() {

key = value = 0;

}

Node(int k, int v) {

key = k;

value = v;

}

}

private HashMap<Integer, Node> map;

private int capacity;

private Node head;

private Node tail;

public Solution48(int capacity) {

this.capacity = capacity;

map = new HashMap<Integer, Node>();

head = new Node();

tail = new Node();

head.prev = null;

head.next = tail;

tail.prev = head;

tail.next = null;

}

public void set(int key, int value) {

Node node;

if (map.containsKey(key)) {

node = map.get(key);

node.value = value;

detach(node);

attach(node);

}

else {

if (map.size() == capacity) {

node = tail.prev;

detach(node);

map.remove(node.key);

}

node = new Node(key, value);

attach(node);

map.put(key, node);

}

}

public int get(int key) {

if (map.containsKey(key)) {

Node node = map.get(key);

detach(node);

attach(node);

return node.value;

}

return -1;

}

private void detach(Node node) {

node.prev.next = node.next;

node.next.prev = node.prev;

}

private void attach(Node node) {

node.next = head.next;

head.next.prev = node;

head.next = node;

node.prev = head;

}

public static void main(String ...args) {

Solution48 s48 = new Solution48(2);

s48.set(1, 9);

s48.set(0, 10);

s48.get(1);

s48.get(1);

s48.get(0);

s48.set(2, 8);

System.out.println(s48.get(0));

System.out.println(s48.get(1));

System.out.println(s48.get(2));

}

}