力扣labuladong一刷day53天LFU 算法

一、460. LFU 缓存

题目链接：https://leetcode.cn/problems/lfu-cache/description/

class LFUCache {HashMap<Integer, Integer> ktv;HashMap<Integer, Integer> ktf;HashMap<Integer, LinkedHashSet<Integer>> ftk;int cap;int minFreq;public LFUCache(int capacity) {ktv = new HashMap<>();ktf = new HashMap<>();ftk = new HashMap<>();cap = capacity;minFreq = 0;}public int get(int key) {if (!ktv.containsKey(key)) {return -1;}Integer v = ktv.get(key);up(key);return v;}private void up(int key) {Integer f = ktf.get(key);ftk.get(f).remove(key);ftk.putIfAbsent(f+1, new LinkedHashSet<>());ftk.get(f + 1).add(key);ktf.put(key, f+1);if (ftk.get(f).isEmpty()) {ftk.remove(f);if (minFreq == f) {minFreq++;}}}public void put(int key, int value) {if (ktv.containsKey(key)) {ktv.put(key, value);up(key);return;}if (ktv.size() == cap) {Integer next = ftk.get(minFreq).iterator().next();ftk.get(minFreq).remove(next);if (ftk.get(minFreq).isEmpty()) {ftk.remove(minFreq);}ktv.remove(next);ktf.remove(next);}ktv.put(key, value);ktf.put(key, 1);ftk.putIfAbsent(1, new LinkedHashSet<>());ftk.get(1).add(key);minFreq = 1;}}/*** Your LFUCache object will be instantiated and called as such:* LFUCache obj = new LFUCache(capacity);* int param_1 = obj.get(key);* obj.put(key,value);*/