"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:
311111 2222233333 4444455555 66666755555 44444 10000 88888 22222 11111 23333
Sample Output:
510000 23333 44444 55555 88888 使用couple记录是否有配偶 使用flag标记是否配偶到场 注意：最后不要输出换行，不然一旦没有输出，那么就有两个换行了！
1 #include2 #include 3 using namespace std; 4 int main() 5 { 6 int n, m, boy, girl, id; 7 int couple[100005], flag[100005]; 8 set guests, res; 9 cin >> n;10 fill(couple, couple + 100005, -1);11 fill(flag, flag + 100005, 0);12 while (n--)13 {14 cin >> boy >> girl;15 couple[boy] = girl;16 couple[girl] = boy;17 }18 cin >> m;19 while (m--)20 {21 cin >> id;22 guests.insert(id);23 if (couple[id] == -1)24 continue;25 else if (flag[id] == 0)//对偶没有来26 {27 flag[id] = 1;28 flag[couple[id]] = 1;29 }30 else if (flag[id] == 1)//对偶来了31 {32 flag[id] = -1;33 flag[couple[id]] = -1;34 }35 }36 for (auto a : guests)37 {38 if (flag[a] != -1)39 res.insert(a);40 }41 cout << res.size() << endl;42 for (auto a : res)43 printf("%s%05d", (a == *(res.begin()) ? "" : " "), a);44 return 0;45 }