link1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97class LFUCache {
class Node {
int key, val, cnt;
Node prev, next;
Node(int key, int val) {
this.key = key;
this.val = val;
cnt = 1;
}
}
class DLList {
Node head, tail;
int size;
DLList() {
head = new Node(0, 0);
tail = new Node(0, 0);
head.next = tail;
tail.prev = head;
}
void add(Node node) {
head.next.prev = node;
node.next = head.next;
node.prev = head;
head.next = node;
size++;
}
void remove(Node node) {
node.prev.next = node.next;
node.next.prev = node.prev;
size--;
}
Node removeLast() {
if (size > 0) {
Node node = tail.prev;
remove(node);
return node;
}
else return null;
}
}
int capacity, size, min;
Map<Integer, Node> nodeMap;
Map<Integer, DLList> countMap;
public LFUCache(int capacity) {
this.capacity = capacity;
this.size=0;
this.min=1;
nodeMap = new HashMap<>();
countMap = new HashMap<>();
}
public int get(int key) {
Node node = nodeMap.get(key);
if (node == null) return -1;
update(node);
return node.val;
}
public void put(int key, int value) {
if (capacity == 0) return;
Node node;
if (nodeMap.containsKey(key)) {
node = nodeMap.get(key);
node.val = value;
update(node);
}
else {
node = new Node(key, value);
nodeMap.put(key, node);
if (size == capacity) {
DLList lastList = countMap.get(min);
nodeMap.remove(lastList.removeLast().key);
size--;
}
size++;
min = 1;
DLList newList = countMap.getOrDefault(node.cnt, new DLList());
newList.add(node);
countMap.put(node.cnt, newList);
}
}
private void update(Node node) {
DLList oldList = countMap.get(node.cnt);
oldList.remove(node);
if (node.cnt == min && oldList.size == 0) min++;
node.cnt++;
DLList newList = countMap.getOrDefault(node.cnt, new DLList());
newList.add(node);
countMap.put(node.cnt, newList);
}
}
link