CF 5A Chat Server's Outgoing Traffic(字符串模拟)

Polychat是一款新项目,包含聊天功能。服务器处理三种命令:添加用户、移除用户和发送消息。发送消息会产生流量,按消息长度乘以当前在线用户数计算。题目要求计算处理一系列命令后的总流量。

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Chat Server's Outgoing Traffic

Time Limit: 1000ms
Memory Limit: 65536KB
This problem will be judged on  CodeForces. Original ID:  5A
64-bit integer IO format:  %I64d      Java class name:  (Any)
Type: 
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  • Polycarp is working on a new project called "Polychat". Following modern tendencies in IT, he decided, that this project should contain chat as well. To achieve this goal, Polycarp has spent several hours in front of his laptop and implemented a chat server that can process three types of commands:

    • Include a person to the chat ('Add' command).
    • Remove a person from the chat ('Remove' command).
    • Send a message from a person to all people, who are currently in the chat, including the one, who sends the message ('Send' command).

    Now Polycarp wants to find out the amount of outgoing traffic that the server will produce while processing a particular set of commands.

    Polycarp knows that chat server sends no traffic for 'Add' and 'Remove' commands. When 'Send' command is processed, server sends l bytes to each participant of the chat, where l is the length of the message.

    As Polycarp has no time, he is asking for your help in solving this problem.

    Input

    Input file will contain not more than 100 commands, each in its own line. No line will exceed 100 characters. Formats of the commands will be the following:

    • +<name> for 'Add' command.
    • -<name> for 'Remove' command.
    • <sender_name>:<message_text> for 'Send' command.

    <name> and <sender_name> is a non-empty sequence of Latin letters and digits. <message_text> can contain letters, digits and spaces, but can't start or end with a space. <message_text> can be an empty line.

    It is guaranteed, that input data are correct, i.e. there will be no 'Add' command if person with such a name is already in the chat, there will be no 'Remove'command if there is no person with such a name in the chat etc.

    All names are case-sensitive.

    Output

    Print a single number — answer to the problem.

    Sample Input

    Input
    +Mike
    Mike:hello
    +Kate
    +Dmitry
    -Dmitry
    Kate:hi
    -Kate
    Output
    9
    Input
    +Mike
    -Mike
    +Mike
    Mike:Hi I am here
    -Mike
    +Kate
    -Kate
    Output
    14

    Source

    题意:

    一个聊天服务器,"+"+人名表示该人加入聊天,"-"+人名表示该退出入聊天,人名后面冒号后面的内容表示该人发的消息,一个人发的消息当前聊天的人都可以接受到,问一共接收到多少个字符.

    简单模拟,注意:发的消息在冒号后面,


    AC代码:

    #include <iostream>
    #include <cstring>
    #include <cstdio>
    using namespace std;
    int main()
    {
        char a[100];
        int sum=0;
        int ans=0;
        while(gets(a))
        {
            int len=strlen(a);
            if(a[0]=='+')
                sum++;
            else if(a[0]=='-')
                sum--;
            else
            {
                int p=0;
                for(int i=0;i<len;i++)
                    if(a[i]==':')
                        p=i;
                ans+=(len-p-1)*sum;
            }
        }
        cout<<ans<<endl;
        return 0;
    }


    ### 使用VC++通过蓝牙发送字符串 为了实现在Windows环境下使用Visual C++ (VC++) 发送字符串数据到其他设备,通常会涉及到Winsock库以及Bluetooth API。下面提供了一个简单的例子来展示如何设置并利用这些API完成基本的数据传输功能。 #### 初始化环境与连接建立 首先需要确保计算机上已经安装了必要的支持包以便能够访问蓝牙服务,并且目标接收端处于可发现状态。程序启动前应确认本地机器已成功配对过目的地址。 ```cpp #include <windows.h> #include <winsock2.h> #include <ws2bth.h> // Bluetooth socket definitions #pragma comment(lib,"Ws2_32.lib") SOCKET ConnectToBluetoothDevice(const char* address){ WSADATA wsaData; WSAStartup(MAKEWORD(2, 2), &wsaData); SOCKADDR_BTH sockAddrBth = {0}; SOCKET connectSocket; // Convert the string representation of device address into BTH_ADDR format. sscanf_s(address,"%8X-%4hX-%4hX-%2hhX%2hhX-%2hhX%2hhX%2hhX%2hhX", &(sockAddrBth.btAddr)); // Specify that we want to use RFCOMM protocol with no security requirements. sockAddrBth.addressFamily = AF_BTH; sockAddrBth.port = BT_PORT_ANY; // Create a new socket for communication over an outgoing connection. connectSocket = socket(AF_BTH, SOCK_STREAM, BTHPROTO_RFCOMM); if(connectSocket != INVALID_SOCKET){ int result = connect(connectSocket,(SOCKADDR*)&sockAddrBth,sizeof(SOCKADDR_BTH)); if(result == SOCKET_ERROR){ closesocket(connectSocket); return NULL; } }else{ return NULL; } return connectSocket; } ``` 此部分代码负责创建一个指向远程蓝牙装置的新套接字,并尝试与其建立RFCOMM类型的链接[^1]。 #### 数据传送过程 一旦建立了有效的通信链路,则可以通过send函数向对方传递信息: ```cpp void SendStringOverBluetooth(SOCKET hSocket,const std::string& message){ const char *buffer=message.c_str(); size_t length=message.length(); send(hSocket, buffer, static_cast<int>(length), 0); } // Remember to close the socket when done: closesocket(hSocket); WSACleanup(); ``` 上述片段展示了怎样把C++中的`std::string`对象转换成字符数组形式并通过现有的socket句柄发出给另一方[^2]。 请注意,在实际应用中还需要处理错误情况、超时机制以及其他可能影响稳定性的因素;此外,对于不同版本的操作系统可能会存在细微差异,因此建议查阅最新的官方文档获取最准确的信息。
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