algorithmic problem about vine prices

vine.cpp

#include <iostream>
#include <vector>
#include <unordered_map>
#include <string>

using namespace std;

unordered_map<string, int> cacheMaxPrices;

int maxPrice(vector<int> &prices, int start, int end){
    if (end == start){
        return 0;
    }

    string cacheKey = to_string(start) + "," + to_string(end);
    if (cacheMaxPrices.find(cacheKey) != cacheMaxPrices.end()){
        return cacheMaxPrices[cacheKey];
    }

    int yearsPast = start + prices.size() - end + 1;
    int valueStart = prices[start] * yearsPast + maxPrice(prices, start + 1, end);
    int valueEnd = prices[end-1] * yearsPast + maxPrice(prices, start, end - 1);
    int res = valueStart > valueEnd ? valueStart : valueEnd;
    cacheMaxPrices[cacheKey] = res;

    return res;
}

int main(){
    int count;
    cin>>count;
    vector<int> prices;
    for(int i = 0; i<count; i++){
        int price;
        cin>>price;
        prices.push_back(price);
    }

    int result = maxPrice(prices, 0, prices.size());
    cout<<result<<endl;

    return 0;
}