1import java.util.*;
2
3public List<Map<String, Object>> calculateCapitalGainLoss(List<Map<String, Object>> stocks) {
4    Map<String, List<Integer>> buyPrices = new HashMap<>();
5    Map<String, Integer> netGains = new HashMap<>();
6
7    for (Map<String, Object> stock : stocks) {
8        String name = (String)stock.get("stock_name");
9        String operation = (String)stock.get("operation");
10        int price = (int)stock.get("price");
11
12        if (operation.equals("Buy")) {
13            buyPrices.putIfAbsent(name, new LinkedList<>());
14            buyPrices.get(name).add(price);
15        } else if (operation.equals("Sell")) {
16            int buyPrice = buyPrices.get(name).remove(0);
17            int gainLoss = price - buyPrice;
18            netGains.put(name, netGains.getOrDefault(name, 0) + gainLoss);
19        }
20    }
21
22    List<Map<String, Object>> result = new ArrayList<>();
23    for (String name : netGains.keySet()) {
24        Map<String, Object> entry = new HashMap<>();
25        entry.put("stock_name", name);
26        entry.put("capital_gain_loss", netGains.get(name));
27        result.add(entry);
28    }
29    return result;
30}

1#include <iostream>
2#include <vector>
3#include <string>
#include <unordered_map>
#include <deque>
#include <algorithm>

struct Stock {
    std::string stock_name;
    std::string operation;
    int operation_day;
    int price;
};

bool compare(Stock a, Stock b) {
    return a.operation_day < b.operation_day;
}

std::vector<std::pair<std::string, int>> calculateCapitalGainLoss(std::vector<Stock> stocks) {
    std::unordered_map<std::string, std::deque<int>> buyPrices;
    std::unordered_map<std::string, int> netGains;

    std::sort(stocks.begin(), stocks.end(), compare);

    for (auto& stock : stocks) {
        if (stock.operation == "Buy") {
            buyPrices[stock.stock_name].push_back(stock.price);
        } else if (stock.operation == "Sell") {
            int buyPrice = buyPrices[stock.stock_name].front();
            buyPrices[stock.stock_name].pop_front();
            int gainLoss = stock.price - buyPrice;
            netGains[stock.stock_name] += gainLoss;
        }
    }

    std::vector<std::pair<std::string, int>> result;
    for (const auto& pair : netGains) {
        result.push_back(pair);
    }

    return result;
}