PAT甲级1121 Damn Single

“Damn Single (单身狗)” is the Chinese nickname for someone who is being single. You are supposed to find those who are alone in a big party, so they can be taken care of.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤ 50,000), the total number of couples. Then N lines of the couples follow, each gives a couple of ID’s which are 5-digit numbers (i.e. from 00000 to 99999). After the list of couples, there is a positive integer M (≤ 10,000) followed by M ID’s of the party guests. The numbers are separated by spaces. It is guaranteed that nobody is having bigamous marriage (重婚) or dangling with more than one companion.

Output Specification:

First print in a line the total number of lonely guests. Then in the next line, print their ID’s in increasing order. The numbers must be separated by exactly 1 space, and there must be no extra space at the end of the line.

Sample Input:

3
11111 22222
33333 44444
55555 66666
7
55555 44444 10000 88888 22222 11111 23333

Sample Output:

5
10000 23333 44444 55555 88888

思路

PAT乙级1065 单身狗
这里没有复制，重新写了一遍

#include <iostream>
#include <algorithm>
#include <map>
#include <vector>
using namespace std;
map<int, int> cp;
map<int, bool> arrive;
int main()
{int N;cin >> N;for (int i = 0; i < N; i++){int a, b;cin >> a >> b;cp[a] = b;cp[b] = a;}int M;cin >> M;vector<int> party;for (int i = 0; i < M; i++){int guest;cin >> guest;party.push_back(guest);arrive[guest] = true;}vector<int> single;for (int i = 0; i < party.size(); i++){if (cp.find(party[i]) != cp.end()){if (arrive.find(cp[party[i]]) == arrive.end())single.push_back(party[i]);}elsesingle.push_back(party[i]);}sort(single.begin(), single.end());cout << single.size() << endl;for (int i = 0; i < single.size(); i++){if (i != 0)printf(" ");printf("%05d", single[i]);}system("pause");return 0;
}