题目连接：http://codeforces.com/contest/21/problem/A
题目大意:判断字符串是否符合要求
题目思路：直接处理字符串
A. Jabber ID
time limit per test
2 seconds
memory limit per test
64 megabytes
input
standard input
output
standard output
Jabber ID on the national Berland service ?Babber? has a form <username>@<hostname>[/resource], where
- <username> — is a sequence of Latin letters (lowercase or uppercase), digits or underscores characters ?_?, the length of <username> is between 1 and 16, inclusive.
- <hostname> — is a sequence of word separated by periods (characters ?.?), where each word should contain only characters allowed for <username>, the length of each word is between 1 and 16, inclusive. The length of <hostname> is between 1 and 32, inclusive.
- <resource> — is a sequence of Latin letters (lowercase or uppercase), digits or underscores characters ?_?, the length of <resource> is between 1 and 16, inclusive.
There are the samples of correct Jabber IDs: mike@codeforces.com, 007@en.codeforces.com/contest.
Your task is to write program which checks if given string is a correct Jabber ID.
Input
The input contains of a single line. The line has the length between 1 and 100 characters, inclusive. Each characters has ASCII-code between 33 and 127, inclusive.
Output
Print YES or NO.
Sample test(s)
Input
mike@codeforces.com
Output
YES
Input
john.smith@codeforces.ru/contest.icpc/12
Output
NO
#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
bool flag=true;
void parse_user(string s)
{if(s.size()<1||s.size()>16){flag=false;return ;}for(int i=0; i<s.size(); i++){if(!isalpha(s[i])&&!isdigit(s[i])&&s[i]!='_'){flag=false;return ;}}
}
void parse_host(string s)
{if(s.size()<1||s.size()>32){flag=false;return ;}string cc;for(int i=0; i<s.size(); i++){if(s[i]=='.'){if(cc.size()<1||cc.size()>16){flag=false;return ;}for(int j=0; j<cc.size(); j++){if(!isalpha(cc[j])&&!isdigit(cc[j])&&cc[j]!='_'){flag=false;return ;}}cc="";}elsecc+=s[i];}if(cc.size()<1||cc.size()>16){flag=false;return ;}for(int j=0; j<cc.size(); j++){if(!isalpha(cc[j])&&!isdigit(cc[j])&&cc[j]!='_'){flag=false;return ;}}
}
void parse_res(string s)
{if(s.size()<1||s.size()>16)flag=false;for(int i=0; i<s.size(); i++){if(!isalpha(s[i])&&!isdigit(s[i])&&s[i]!='_'){flag=false;return ;}}
}
int main()
{string str;string username,hostname,resource;while(cin>>str){flag=true;int cur=0;while(cur<str.size()&&str[cur]!='@'){username+=str[cur];cur++;}if(cur>=str.size()){flag=false;}parse_user(username);cur++;while(cur<str.size()&&str[cur]!='/'){hostname+=str[cur];cur++;}parse_host(hostname);if(cur<str.size()){cur++;while(cur<str.size()){resource+=str[cur];cur++;}parse_res(resource);}if(flag)printf("YES\n");else printf("NO\n");}return 0;
}