answer2.cpp

#include <iostream>
#include <map>
#include <cmath>
#include <ctime> 
#include <vector>
using namespace std;

template <typename T>
class Cache {
public:
    struct CacheData{
        string key;
        T value;
        time_t lastAccessTime;
    };

    static const int primeNum = 2039;
    static const int maxSize = 5;
    vector<CacheData> data[Cache::primeNum];

    CacheData* get(string key) {
        int index = hashFunc(key);
        for(CacheData cacheData : data[index]) {
            if (cacheData.key == key) {
                return &cacheData;
            }
        }
        return NULL;
    }

    void put(string key, T value, double weight) {
        int index = hashFunc(key);
        int size = data[index].size();

        // Set value
        for(CacheData cacheData : data[index]) {
            if (cacheData.key == key) {
                cout << "set Value" << endl;
                cacheData.value = value;
                return;
            }
        }

        // Insert value
        if ((size + 1) <= Cache::maxSize) {
            CacheData cacheData;
            cacheData.key = key;
            cacheData.value = value;
            cacheData.lastAccessTime = time(0);
            data[index].push_back(cacheData);
            cout << "push_back" << endl;
        } else { // invalidate
            int leastScoreIndex = 0;
            double leastScore = LC_MAX;
            for(int i = 0; i < data[index].size(); i++) {
                double score = getScore(data[index][i], weight);
                if (score < leastScore) {
                    cout << data[index][i].key << " score:" << score << endl;
                    leastScoreIndex = i;
                    leastScore = score;
                }
            }
            cout << "invalidate key:" << data[index][leastScoreIndex].key << endl;
            data[index][leastScoreIndex].key = key;
            data[index][leastScoreIndex].value = value;
            data[index][leastScoreIndex].lastAccessTime = time(0);
        }
    }

    double getScore(CacheData cacheData, double weight) {
        time_t currentTime = time(0);
        if (currentTime != cacheData.lastAccessTime) {
            return weight / log(currentTime / cacheData.lastAccessTime);
        } else {
            return weight / -100;
        }
    }

    int hashFunc(string s) {
        int total = 0;
        for(char c: s) {
            total += (int)c;
        }
        total %= primeNum;
        return total;
    }
};

int main() {
    Cache<int> cache;
    cache.put("a", 1, 1.0);
    cache.put("c", 1, 1.0);
    cache.put("e", 1, 1.0);
    cache.put("g", 1, 1.0);
    cache.put("i", 1, 1.0);
    cache.put("k", 1, 1.0);
    if(cache.get("a") != NULL)
        cout << cache.get("a")->key << endl;
    return 0;
}