Message Flood——MAP

Message FloodTime Limit:1500MS     Memory Limit:65536KB     64bit IO Format:%lld& %lluSubmit StatusDescriptionWell, how do you feel about mobile phone? Your answer would probably be something like that "It's so convenient and benefits people a lot". However, If you ask Merlin this question on the New Year's Eve, he will definitely answer "What a trouble! I have tokeep my fingers moving on the phone the whole night, because I have so many greeting message to send!" Yes, Merlin has such a long name list of his friends, and he would like to send a greeting message to each of them. What's worse, Merlin has another longname list of senders that have sent message to him, and he doesn't want to send another message to bother them Merlin is so polite that he always replies each message he receives immediately). So, before he begins to send message, he needs to figure to howmany friends are left to be sent. Please write a program to help him. Here is something that you should note. First, Merlin's friend list is not ordered, and each name is alphabetic strings and case insensitive. These names are guaranteed to be not duplicated.Second, some senders may send more than one message to Merlin, therefore the sender list may be duplicated. Third, Merlin is known by so many people, that's why some message senders are even not included in his friend list.InputThere are multiple test cases. In each case, at the first line there are two numbers n and m (1<=n,m<=20000), which is the number of friends and the number of messages he has received. And then there are n lines of alphabetic strings(the length of each willbe less than 10), indicating the names of Merlin's friends, one per line. After that there are m lines of alphabetic strings, which are the names of message senders. The input is terminated by n=0.OutputFor each case, print one integer in one line which indicates the number of left friends he must send.Sample Input

5 3
Inkfish
Henry
Carp
Max
Jericho
Carp
Max
Carp
0

Sample Output

3

题意：5个需要回复短信的人，3个已经回复的短信（有可能是同一个人），问还需要回复多少条短信。

解析：运用map<string,int>，判断int的值是否为0。

具体看代码解析:

#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <map>using namespace std;int main(){int n,m,i,j,k,c;string name;map<string,int> q;while(scanf("%d",&n)!=EOF){if(n == 0)break;scanf("%d",&m);q.clear();for(i = 0;i < n;i++){cin>>name;transform(name.begin(),name.end(),name.begin(),::tolower);//因为不区分大小写，所以调用transform将字母全部转化成小写//transform(name.begin(),name.end(),name.begin(),::toupper);//该语句将字母转化成大些q[name]++;//q[name]不等于0，说明这个人需要回复短信}for(i = 0;i < m;i++){cin>>name;transform(name.begin(),name.end(),name.begin(),::tolower);if(q[name]!=0){q[name] = 0;//q[name]等于0，说明已经回复过了n--;}}printf("%d\n",n);}return 0;}