5A - Chat Servers Outgoing Traffic

最新推荐文章于 2022-02-06 20:46:00 发布

原创最新推荐文章于 2022-02-06 20:46:00 发布 · 531 阅读

0 ·

CC 4.0 BY-SA版权

=====codeforces===== 专栏收录该内容

75 篇文章

订阅专栏

本文介绍了一个聊天服务器如何根据不同的操作指令（添加用户、移除用户、发送消息）来计算其产生的外发流量的方法。通过具体的例子展示了算法实现，并提供了一种使用set和字符串处理的方式来解决该问题。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

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.

Examples

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

题意：

+ 为加入一个人聊天，- 为这个人退出聊天，如果一个人在聊天中，他说一句话，其中所有人（包括自己）都能收到，问整个过程，所有人收到的信息的总长度为多少

使用set 和string 会比较简单，对c++的这些模块不太熟练，写的代码有点奇怪...

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<set>
#include<string>
using namespace std;
int local(char s[])
{
    for(int i=0;s[i];++i)
    {
        if(s[i]==':')
        {
            return i;
        }
    }
}
int main()
{
    set<string> vis;
    char s[205];
    int ans=0;
    while(gets(s))
    {
        if(s[0]=='+')//增加一个人
        {
            string tp=s+1;
            vis.insert(tp);
        }
        else if(s[0]=='-')
        {
            string tp=s+1;
            vis.erase(tp);
        }
        else
        {
            int st=local(s);// 冒号的位置
            string tp(s,s+st);
            if(vis.count(tp))
            {
                ans+=strlen(s+st+1)*vis.size();
            }
        }
    }
    cout <<ans<<endl;
    return 0;
}

这样也是可以AC的

#include<cstdio>
#include<cstring>
int main()
{
    int ans=0,cnt=0;
    char s[205];
    while(gets(s))
    {
        if(s[0]=='+')
        {
            ++cnt;
        }
        else if(s[0]=='-')
        {
            --cnt;
        }
        else
        {
            int tp=0;
            for(int i=0;s[i];++i)
            {
                if(s[i]==':')
                {
                    tp=i;
                    break;
                }
            }
            ans=ans+cnt*strlen(s+tp+1);
        }
    }
    printf("%d\n",ans);
    return 0;
}