ただ書いただけ http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2011

hachi.cpp

#include <algorithm>
#include <iostream>
#include <iterator>
#include <unordered_set>
#include <vector>


int read_i() {
	int t;
	std::cin >> t;
	return t;
}


class People {
private:
	std::vector< std::unordered_set<int> > people;
	int alive;

public:
	People(const int n) {
		alive = n;
		for(int i=0; i<n; i++){
			people.push_back(std::unordered_set<int>());

			for(int j=read_i(); j>0; j--){
				people[i].insert(read_i());
			}
		}
	}

	People(const People& x) {
		std::copy(x.people.begin(), x.people.end(), std::back_inserter(people));
		alive = x.alive;
	}

	void kill(int i, const std::unordered_set<int>& js) {
		for(auto j: js){
			if(i == j){
				continue;
			}

			people[j].clear();
			alive--;
		}
	}

	int run(const int day=1) const {
		if(alive == 1){
			return day - 1;
		}

		for(int d=day; d<30; d++){
			for(int i=0; i<people.size(); i++){
				if(people[i].find(day) == people[i].end()){
					continue;
				}

				std::unordered_set<int> cands;

				for(int j=i+1; j<people.size(); j++){
					if(people[j].find(day) != people[j].end()){
						cands.insert(j);
					}
				}

				if(cands.size() == 0){
					continue;
				}

				cands.insert(i);
				for(const auto c: cands){
					People child(*this);
					child.kill(c, cands);

					const int r = child.run(day+1);
					if(r > 0){
						return r;
					}
				}
			}
		}

		return -1;
	}
};


int main() {
	while(true){
		const int n = read_i();
		if(n == 0){
			break;
		}

		People people(n);
		std::cout << people.run() << std::endl;
	}
}