获取最高薪资PartTimeEmployee姓名的方法返回结果异常问题

我需要实现一个算法，返回薪资最高的PartTimeEmployee姓名，预期结果是"Wills"，但当前方法总是返回数组第一个位置的名字"Muwana"。

当前方法代码 #

public string PartTimeEmployeeWithHighestSalary()
{
    string name = employees[0].GetName();
    double salary = employees[0].GetSalary();

    for (int i = 0; i < count; i++)
    {
        if (employees[i].GetSalary() > salary && employees[i] is PartTimeEmployee)
        {
            salary = employees[i].GetSalary();
            name = employees[i].GetName();
        }
    }
    return name;
}

程序测试代码 #

static void Main(string[] args)
{
    Employee EmpS1 = new ServiceEmployee("S123", "Muwana", "Sein",1000);
    Employee EmpS2 = new ServiceEmployee("S124", "Prince", "Jack",1500);
    Employee EmpS3 = new ServiceEmployee("S125", "Matengu", "Prince",6000);
    Employee EmpP1 = new PartTimeEmployee("P133", "Mad", "Max",2500);
    Employee EmpP2 = new PartTimeEmployee("P134", "Wills", "Sanjay",3000);
    Employee EmpP3 = new PartTimeEmployee("P135", "Rick", "Sanchez",1000);
    Employee EmpM1 = new ManagementEmployee("M143", "Morty", "Smith",1500);
    Employee EmpM2 = new ManagementEmployee("M143", "Summer", "Smith",6500);
    Employee EmpM3 = new ManagementEmployee("M144", "Beth", "Smith",6500);

    HRDepartment company = new HRDepartment(500);

    company.AddEmployee(EmpS1);
    company.AddEmployee(EmpS2);
    company.AddEmployee(EmpS3);
    company.AddEmployee(EmpP1);
    company.AddEmployee(EmpP2);
    company.AddEmployee(EmpP3);
    company.AddEmployee(EmpM1);
    company.AddEmployee(EmpM2);
    company.AddEmployee(EmpM3);

    //-1. PartTime employee with highest salary
    Console.WriteLine("PartTime employee with highest salary:{0}",company.PartTimeEmployeeWithHighestSalary());
}

错误原因 #

当前代码的核心问题是初始值没有限定为PartTimeEmployee类型：

• 直接用数组第一个非兼职员工（ServiceEmployee类型的Muwana）初始化name和salary，初始值本身不符合筛选条件；
• 若后续兼职员工薪资未超过初始值，会错误返回非兼职员工的名字；即使有更高薪资的兼职员工，也可能因count未正确统计员工数量等隐性问题导致遍历不完整。

修复方案 #

方案一：初始化最低薪资，遍历筛选兼职员工 #

将初始薪资设为double.MinValue，遍历所有员工时先判断是否为兼职员工，再比较薪资更新结果：

public string PartTimeEmployeeWithHighestSalary()
{
    string name = null;
    double highestSalary = double.MinValue;

    for (int i = 0; i < count; i++)
    {
        // 先判断类型，并用模式匹配直接转换为PartTimeEmployee
        if (employees[i] is PartTimeEmployee partTimeEmp)
        {
            double currentSalary = partTimeEmp.GetSalary();
            if (currentSalary > highestSalary)
            {
                highestSalary = currentSalary;
                name = partTimeEmp.GetName();
            }
        }
    }
    // 可根据需求处理无兼职员工的情况，比如返回提示文本
    return name ?? "No PartTime Employees";
}

方案二：先找到第一个兼职员工作为初始值 #

先定位第一个兼职员工，以此为初始值再继续比较后续的兼职员工，避免初始值无效：

public string PartTimeEmployeeWithHighestSalary()
{
    // 先定位第一个兼职员工
    int startIndex = 0;
    while (startIndex < count && !(employees[startIndex] is PartTimeEmployee))
    {
        startIndex++;
    }

    // 没有找到兼职员工的情况
    if (startIndex >= count)
    {
        return "No PartTime Employees";
    }

    string name = employees[startIndex].GetName();
    double highestSalary = employees[startIndex].GetSalary();

    // 从第一个兼职员工的下一位开始遍历
    for (int i = startIndex + 1; i < count; i++)
    {
        if (employees[i] is PartTimeEmployee partTimeEmp)
        {
            double currentSalary = partTimeEmp.GetSalary();
            if (currentSalary > highestSalary)
            {
                highestSalary = currentSalary;
                name = partTimeEmp.GetName();
            }
        }
    }
    return name;
}

内容的提问来源于stack exchange，提问作者Prince Sein