本关任务：有三个候选人，每个选民只能投一票，写一程序，用结构体存储数据，求出得票结果。 三个候选人为 "Li"， "Zhang"，"Sun"。

要编写一个程序来计算三位候选人 "Li"、"Zhang" 和 "Sun" 的得票结果，我们可以创建一个结构体来存储每个候选人的名字和对应的投票数。首先，定义一个结构体 `Candidate`：

#include <string>
#include <map>

struct Candidate {
    std::string name;
    int votes;

    // 默认构造函数和用于比较名称的默认析构函数
    Candidate(const std::string& n = "") : name(n), votes(0) {}
    bool operator<(const Candidate& other) const { return name < other.name; }
};

接下来，创建一个 map 来存储候选人的名字和投票计数，初始化并允许用户输入投票：

int main() {
    std::map<Candidate, int> electionResults;

    // 初始化候选人
    Candidate li("Li");
    Candidate zhang("Zhang");
    Candidate sun("Sun");

    electionResults[li] = 0;
    electionResults[zhang] = 0;
    electionResults[sun] = 0;

    // 接收用户投票
    int totalVotes;
    std::cout << "Enter the total number of votes: ";
    std::cin >> totalVotes;

    for (int i = 0; i < totalVotes; ++i) {
        std::string voterChoice;
        std::cout << "Enter vote for Li, Zhang or Sun (case-sensitive): ";
        std::cin >> voterChoice;

        if (voterChoice == "Li") {
            electionResults[li]++;
        } else if (voterChoice == "Zhang") {
            electionResults[zhang]++;
        } else if (voterChoice == "Sun") {
            electionResults[sun]++;
        } else {
            std::cerr << "Invalid choice! Please try again.\n";
            continue;
        }
    }

    // 打印得票结果
    for (const auto& result : electionResults) {
        std::cout << result.first.name << " received " << result.second << " votes.\n";
    }

    return 0;
}