假设某银行网点有五个服务窗口，分别为三个对私、一个对公和一个外币窗口。银行服务的原则是先来先服务。通常对私业务人很多，其它窗口人则较少，可临时改为对私服务。假设当对私窗口等待服务的客户（按实际服务窗口）平均排队人数超过（大于或等于）7人时，等待客户将可能有抱怨，影响服务质量，此时银行可临时将其它窗口中一个或两个改为对私服务，当平均排队客户少于7人时，将立即恢复原有业务。设计一个程序用来模拟银行服务。

下面是一个简单的银行服务模拟程序的示例代码，供您参考：

import random
import time

class Bank:
    def __init__(self, num_private_win, num_public_win, num_foreign_win):
        self.num_private_win = num_private_win # 对私窗口数量
        self.num_public_win = num_public_win # 对公窗口数量
        self.num_foreign_win = num_foreign_win # 外币窗口数量
        self.waiting_private = [] # 对私客户等待队列
        self.waiting_public = [] # 对公客户等待队列
        self.waiting_foreign = [] # 外币客户等待队列
        self.private_win_in_use = [False] * num_private_win # 记录对私窗口是否在使用
        self.public_win_in_use = [False] * num_public_win # 记录对公窗口是否在使用
        self.foreign_win_in_use = [False] * num_foreign_win # 记录外币窗口是否在使用
        self.private_win_service_time = [0] * num_private_win # 记录对私窗口已服务时间
        self.public_win_service_time = [0] * num_public_win # 记录对公窗口已服务时间
        self.foreign_win_service_time = [0] * num_foreign_win # 记录外币窗口已服务时间
        self.private_win_service_customer = [None] * num_private_win # 记录对私窗口当前服务客户
        self.public_win_service_customer = [None] * num_public_win # 记录对公窗口当前服务客户
        self.foreign_win_service_customer = [None] * num_foreign_win # 记录外币窗口当前服务客户
    
    def add_customer(self, customer):
        if customer.service_type == 'private':
            self.waiting_private.append(customer)
        elif customer.service_type == 'public':
            self.waiting_public.append(customer)
        else:
            self.waiting_foreign.append(customer)
    
    def serve_customer(self):
        # 随机选择一个窗口类型，以便进行临时调整
        win_type = random.choice(['private', 'public', 'foreign'])
        
        # 如果对私排队人数超过7人，将一个其它窗口改为对私服务
        if len(self.waiting_private) >= 7:
            if win_type == 'public':
                win_index = random.randint(0, self.num_public_win-1)
                self.private_win_in_use[win_index] = True
                self.public_win_in_use[win_index] = False
                self.private_win_service_customer[win_index] = self.waiting_public.pop(0)
            elif win_type == 'foreign':
                win_index = random.randint(0, self.num_foreign_win-1)
                self.private_win_in_use[win_index] = True
                self.foreign_win_in_use[win_index] = False
                self.private_win_service_customer[win_index] = self.waiting_foreign.pop(0)
            else:
                for i, in_use in enumerate(self.public_win_in_use):
                    if not in_use:
                        self.private_win_in_use[i] = True
                        self.public_win_in_use[i] = False
                        self.private_win_service_customer[i] = self.waiting_public.pop(0)
                        break
                else:
                    for i, in_use in enumerate(self.foreign_win_in_use):
                        if not in_use:
                            self.private_win_in_use[i] = True
                            self.foreign_win_in_use[i] = False
                            self.private_win_service_customer[i] = self.waiting_foreign.pop(0)
                            break
        # 否则，将所有窗口恢复到原有业务
        else:
            for i in range(self.num_private_win):
                if self.private_win_in_use[i]:
                    self.private_win_in_use[i] = False
                    if self.private_win_service_customer[i].service_type == 'private':
                        self.waiting_private.append(self.private_win_service_customer[i])
                    elif self.private_win_service_customer[i].service_type == 'public':
                        self.waiting_public.append(self.private_win_service_customer[i])
                    else:
                        self.waiting_foreign.append(self.private_win_service_customer[i])
                    self.private_win_service_customer[i] = None
            for i in range(self.num_public_win):
                if self.public_win_in_use[i]:
                    self.public_win_in_use[i] = False
                    if self.public_win_service_customer[i].service_type == 'public':
                        self.waiting_public.append(self.public_win_service_customer[i])
                    else:
                        self.waiting_foreign.append(self.public_win_service_customer[i])
                    self.public_win_service_customer[i] = None
            for i in range(self.num_foreign_win):
                if self.foreign_win_in_use[i]:
                    self.foreign_win_in_use[i] = False
                    self.waiting_foreign.append(self.foreign_win_service_customer[i])
                    self.foreign_win_service_customer[i] = None
        
        # 对私服务
        for i in range(self.num_private_win):
            if not self.private_win_in_use[i] and self.waiting_private:
                self.private_win_in_use[i] = True
                self.private_win_service_customer[i] = self.waiting_private.pop(0)
        # 对公服务
        for i in range(self.num_public_win):
            if not self.public_win_in_use[i] and self.waiting_public:
                self.public_win_in_use[i] = True
                self.public_win_service_customer[i] = self.waiting_public.pop(0)
        # 外币服务
        for i in range(self.num_foreign_win):
            if not self.foreign_win_in_use[i] and self.waiting_foreign:
                self.foreign_win_in_use[i] = True
                self.foreign_win_service_customer[i] = self.waiting_foreign.pop(0)
    
    def print_status(self):
        print('对私窗口状态：', self.private_win_in_use)
        print('对公窗口状态：', self.public_win_in_use)
        print('外币窗口状态：', self.foreign_win_in_use)
        print('对私客户等待队列：', self.waiting_private)
        print('对公客户等待队列：', self.waiting_public)
        print('外币客户等待队列：', self.waiting_foreign)

class Customer:
    def __init__(self, id, service_type):
        self.id = id # 客户ID
        self.service_type = service_type # 服务类型，'private'、'public'或'foreign'
    
    def __repr__(self):
        return 'Customer {}'.format(self.id)

def run_bank_simulation(num_private_win, num_public_win, num_foreign_win, max_time):
    bank = Bank(num_private_win, num_public_win, num_foreign_win)
    customers = []
    for i in range(100):
        if i % 5 == 0:
            customers.append(Customer(i, 'public'))
        elif i % 7 == 0:
            customers.append(Customer(i, 'foreign'))
        else:
            customers.append(Customer(i, 'private'))
    
    start_time = time.time()
    current_time = 0
    while current_time < max_time:
        # 添加新客户
        if customers and random.random() < 0.5:
            bank.add_customer(customers.pop(0))
        # 服务客户
        bank.serve_customer()
        # 输出状态
        print('Time: {:.2f}'.format(current_time))
        bank.print_status()
        time.sleep(1)
        current_time = time.time() - start_time

run_bank_simulation(3, 1, 1, 60)

在这个程序中，我们定义了 `Bank` 类来表示银行，其中包括服务窗口数量、等待队列和窗口状态等信息，并定义了 `add_customer` 和 `serve_customer` 方法来添加客户和服务客户。我们还定义了 `Customer` 类来表示客户，包括客户ID和服务类型。

在 `run_bank_simulation` 函数中，我们初始化了银行和一些客户，然后开始模拟服务过程。在每个时间步长中，我们随机决定是否添加新客户，然后调用 `serve_customer` 方法来服务现有客户。最后输出当前银行状态，并使用 `time.sleep` 函数来模拟客户等待的时间。

当对私窗口等待服务的客户平均排队人数超过7人时，等待客户将可能有抱怨，为了避免影响服务质量，程序会根据一定的规则将其它窗口中一个或两个改为对私服务，当平均排队客户少于7人时，程序将立即恢复原有业务。具体实现可以参考 `serve_customer` 方法中的代码。