B. Chat Order
time limit per test
3 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Polycarp is a big lover of killing time in social networks. A page with a chatlist in his favourite network is made so that when a message is sent to some friend, his friend's chat rises to the very top of the page. The relative order of the other chats doesn't change. If there was no chat with this friend before, then a new chat is simply inserted to the top of the list.
Assuming that the chat list is initially empty, given the sequence of Polycaprus' messages make a list of chats after all of his messages are processed. Assume that no friend wrote any message to Polycarpus.
Input
The first line contains integer n (1 ≤ n ≤ 200 000) — the number of Polycarpus' messages. Next n lines enlist the message recipients in the order in which the messages were sent. The name of each participant is a non-empty sequence of lowercase English letters of length at most 10.
Output
Print all the recipients to who Polycarp talked to in the order of chats with them, from top to bottom.
Examples
input
Copy
4 alex ivan roman ivan
output
Copy
ivan roman alex
input
Copy
8 alina maria ekaterina darya darya ekaterina maria alina
output
Copy
alina maria ekaterina darya
Note
意：根据一天的对话，倒着给出说话人的名字。让你正着输出说第一次话的人的名字。比如 abacdabacd，正着说话 =dcab=dcab， 最后一个aa是aa第二次说话，不用输出。
直接正着来，一个名字只输出一次，后面的跳过。
就是把输入的字符串倒着输出就行了，加个map判重
#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <set>
#include <ctime>
#include <cmath>
#include <cctype>
using namespace std;
#define maxn 200005
#define LL long long
int cas=1,T;
map<string,int> visit;
string s[maxn];
int main()
{
int n;
while (scanf("%d",&n)!=EOF)
{
for (int i = 0;i<n;i++)
{
cin >> s[i];
//visit[s[i]]=1;
}
for (int i = n-1;i>=0;i--)
{
if (!visit[s[i]])
cout << s[i] << endl;
visit[s[i]]=1;
}
}
//freopen("in","r",stdin);
//scanf("%d",&T);
//printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
return 0;
}