zoukankan      html  css  js  c++  java
  • CodeForces-501B

    Misha hacked the Codeforces site. Then he decided to let all the users change their handles. A user can now change his handle any number of times. But each new handle must not be equal to any handle that is already used or that was used at some point.

    Misha has a list of handle change requests. After completing the requests he wants to understand the relation between the original and the new handles of the users. Help him to do that.

    Input

    The first line contains integer q (1 ≤ q ≤ 1000), the number of handle change requests.

    Next q lines contain the descriptions of the requests, one per line.

    Each query consists of two non-empty strings old and new, separated by a space. The strings consist of lowercase and uppercase Latin letters and digits. Strings old and new are distinct. The lengths of the strings do not exceed 20.

    The requests are given chronologically. In other words, by the moment of a query there is a single person with handle old, and handle new is not used and has not been used by anyone.

    Output

    In the first line output the integer n — the number of users that changed their handles at least once.

    In the next n lines print the mapping between the old and the new handles of the users. Each of them must contain two strings, old and new, separated by a space, meaning that before the user had handle old, and after all the requests are completed, his handle is new. You may output lines in any order.

    Each user who changes the handle must occur exactly once in this description.

    Examples

    Input

    5
    Misha ILoveCodeforces
    Vasya Petrov
    Petrov VasyaPetrov123
    ILoveCodeforces MikeMirzayanov
    Petya Ivanov
    

    Output

    3
    Petya Ivanov
    Misha MikeMirzayanov
    Vasya VasyaPetrov123
    #include<iostream>
    #include<map>
    #include<string>
    using namespace std;
    int main() {
    	int n;
    	while (cin >> n) {
    		map<string, string> str;
    		while (n--) {
    			string s1, s2;
    			cin >> s1 >> s2;
    			if (!str.count(s1)) str[s2] = s1;
    			else {
    				str[s2] = str[s1];
    				str.erase(s1);
    			}
    		}
    		cout << str.size() << endl;
    		for (map<string, string>::iterator it = str.begin(); it != str.end(); it++)
    			cout << it->second << " " << it->first << endl;
    	}
    	return 0;
    }
    
  • 相关阅读:
    致应届毕业生——程序员的生存法则 转自CSDN 作者:陈丽辉
    TIOBE 8月份编程语言排行榜,F#强势插入
    C–gcc命令行下的参数
    转载sunboy_2050 Android APK反编译详解(附图)
    转载IT168 分析:Python在Linux平台上的发展前景
    PHP 简单学习过程1
    买火车票必须知道的事
    Delphi PointerMath编译指令
    给DropDownList的DataTextField属性绑定两个字段
    通过HttpModule、httpHandlers防止SQL注入式攻击
  • 原文地址:https://www.cnblogs.com/csushl/p/9386504.html
Copyright © 2011-2022 走看看