容器选择全景指南

#include <iostream>
#include <vector>
#include <list>
#include <unordered_map>
#include <set>
#include <chrono>
#include <algorithm>
#include <numeric>

// 模拟不同场景的容器性能
int main() {
    const int N = 20000;

    // 场景1：日志追加（适合 vector）
    // 场景：李眉每天追加运维日志
    {
        std::vector<int> logEntries;
        auto start = std::chrono::high_resolution_clock::now();
        for (int i = 0; i < N; ++i)
            logEntries.push_back(i);
        auto t = std::chrono::duration<double, std::milli>(
            std::chrono::high_resolution_clock::now() - start).count();
        std::cout << "[vector push_back] " << t << " ms\n";
    }

    // 场景2：实时消息队列（适合 deque 或 list）
    // 场景：赵鸣的内容发布系统先消费旧消息、接收新消息
    {
        std::list<int> messages;
        for (int i = 0; i < N / 2; ++i) messages.push_back(i);

        auto start = std::chrono::high_resolution_clock::now();
        for (int i = 0; i < N / 4; ++i) {
            messages.pop_front();          // 消费消息 O(1)
            messages.push_back(N + i);     // 新消息 O(1)
        }
        auto t = std::chrono::duration<double, std::milli>(
            std::chrono::high_resolution_clock::now() - start).count();
        std::cout << "[list pop_front+push_back] " << t << " ms\n";
    }

    // 场景3：用户在线状态（适合 unordered_map）
    // 场景：高英需要频繁查询用户在线状态
    {
        std::unordered_map<int, bool> onlineStatus;
        for (int i = 0; i < N; ++i)
            onlineStatus[i] = (i % 3 == 0);

        auto start = std::chrono::high_resolution_clock::now();
        int count = 0;
        for (int i = 0; i < N * 10; ++i)  // 大量查询
            if (onlineStatus.count(i % N)) ++count;
        auto t = std::chrono::duration<double, std::milli>(
            std::chrono::high_resolution_clock::now() - start).count();
        std::cout << "[unordered_map 200K查询] " << t << " ms, 命中: " << count << "\n";
    }

    // 场景4：排行榜（适合 set/map，天然有序）
    // 场景：杨英的活动排行榜需要按积分排序
    {
        std::set<int, std::greater<int>> leaderboard;
        for (int i = 0; i < N; ++i)
            leaderboard.insert(rand() % 10000);

        std::cout << "\n[set 排行榜 Top 10]\n";
        int rank = 1;
        for (auto it = leaderboard.begin(); rank <= 10 && it != leaderboard.end(); ++it, ++rank)
            std::cout << "  #" << rank << ": " << *it << " 分\n";
    }
}

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

// 飞翔科技各业务模块容器选型总结
struct ContainerChoice {
    std::string module;
    std::string scenario;
    std::string container;
    std::string reason;
};

int main() {
    std::vector<ContainerChoice> choices = {
        {"孔蓝-需求池", "优先级排序", "std::priority_queue",
         "按优先级取最高，底层最大堆 O(log n) push + O(1) top"},
        {"白歌-架构监控", "服务列表（固定数量）", "std::array",
         "微服务数量固定，零开销，编译期检查"},
        {"小崔-缓存层", "KV 缓存", "std::unordered_map",
         "O(1) 平均查找，无需排序"},
        {"黄俪-UI 组件树", "组件嵌套", "std::list",
         "频繁增删子组件，迭代器不失效"},
        {"李眉-服务器日志", "日志追加", "std::vector",
         "连续内存，缓存友好，批量写入"},
        {"赵鸣-内容发布", "消息队列", "std::queue",
         "FIFO 语义清晰，deque 底层双端高效"},
        {"高英-用户排行榜", "有序排名", "std::set",
         "红黑树自动排序，区间查询方便"},
    };

    std::cout << "=== 飞翔科技各模块容器选型 ===\n\n";
    for (const auto& c : choices) {
        std::cout << "【" << c.module << "】" << c.scenario << "\n";
        std::cout << "  选型: " << c.container << "\n";
        std::cout << "  理由: " << c.reason << "\n\n";
    }
}

// 80% 的场景 vector 是最优选择
// 只有在需要：前端增删 / 频繁中间插入删除 / 按键查找 / 迭代器稳定 时才考虑其他

// 如果实际运行时插入很少，vector 的缓存局部性优势可能远超 list 的 O(1) 插入

// unordered_map 元素无序，遍历顺序每次可能不同
// 需要有序遍历时必须用 map