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| 1 | +class Node{ |
| 2 | + var $key; |
| 3 | + var $val; |
| 4 | + var $prev; |
| 5 | + var $next; |
| 6 | + function __construct($key, $val) { |
| 7 | + $this->key = $key; |
| 8 | + $this->val = $val; |
| 9 | + $this->prev = null; |
| 10 | + $this->next = null; |
| 11 | + } |
| 12 | +} |
| 13 | + |
| 14 | +class LRUCache { |
| 15 | + /** |
| 16 | + * @param Integer $capacity |
| 17 | + */ |
| 18 | + function __construct($capacity) { |
| 19 | + $this->capacity = $capacity; |
| 20 | + $this->currentCapacity = 0; |
| 21 | + $this->head = new Node(0, 0); |
| 22 | + $this->tail = new Node(0, 0); |
| 23 | + $this->head->next = $this->tail; |
| 24 | + $this->tail->prev = $this->head; |
| 25 | + $this->map = []; |
| 26 | + } |
| 27 | + |
| 28 | + /** |
| 29 | + * @param Integer $key |
| 30 | + * @return Integer |
| 31 | + */ |
| 32 | + function get($key) { |
| 33 | + if (array_key_exists($key, $this->map)) { |
| 34 | + $node = $this->map[$key]; |
| 35 | + self::removeNode($node); |
| 36 | + self::addToTail($node); |
| 37 | + return $node->val; |
| 38 | + } |
| 39 | + return -1; |
| 40 | + } |
| 41 | + |
| 42 | + /** |
| 43 | + * @param Integer $key |
| 44 | + * @param Integer $value |
| 45 | + * @return NULL |
| 46 | + */ |
| 47 | + function put($key, $value) { |
| 48 | + if (array_key_exists($key, $this->map)) { |
| 49 | + $node = $this->map[$key]; |
| 50 | + self::removeNode($node); |
| 51 | + $node->val = $value; |
| 52 | + $this->map[$key] = $node; |
| 53 | + self::addToTail($node); |
| 54 | + } else { |
| 55 | + if ($this->currentCapacity == $this->capacity) { |
| 56 | + $removeKey = $this->head->next->key; |
| 57 | + self::removeNode($this->head->next); |
| 58 | + unset($this->map[$removeKey]); |
| 59 | + $this->currentCapacity--; |
| 60 | + } |
| 61 | + $newNode = new Node($key, $value); |
| 62 | + $this->map[$key] = $newNode; |
| 63 | + self::addToTail($newNode); |
| 64 | + $this->currentCapacity++; |
| 65 | + } |
| 66 | + } |
| 67 | + |
| 68 | + function removeNode($node) { |
| 69 | + $node->prev->next = $node->next; |
| 70 | + $node->next->prev = $node->prev; |
| 71 | + } |
| 72 | + |
| 73 | + function addToTail($node) { |
| 74 | + $this->tail->prev->next = $node; |
| 75 | + $node->prev = $this->tail->prev; |
| 76 | + $node->next = $this->tail; |
| 77 | + $this->tail->prev = $node; |
| 78 | + } |
| 79 | + |
| 80 | +} |
| 81 | + |
| 82 | +/** |
| 83 | + * Your LRUCache object will be instantiated and called as such: |
| 84 | + * $obj = LRUCache($capacity); |
| 85 | + * $ret_1 = $obj->get($key); |
| 86 | + * $obj->put($key, $value); |
| 87 | + */ |
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