Submission #45088

#	Time	Username	Problem	Language	Result	Execution time	Memory
45088		qoo2p5	One-Way Streets (CEOI17_oneway)	C++17	0 / 100	27 ms	632 KiB

oneway

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;

#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define mp make_pair
#define pb push_back

bool mini(auto &x, const auto &y) {
	if (y < x) {
		x = y;
		return 1;
	}
	return 0;
}

bool maxi(auto &x, const auto &y) {
	if (y > x) {
		x = y;
		return 1;
	}
	return 0;
}

void run();

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	run();
	return 0;
}

const int N = (int) 22;

struct E {
	int a, b;
};

int n, m;
E e[N];
vector<pair<int, int>> g[N];
bool can[N][N];
bool can_left[N], can_right[N];
int p;
int x[N], y[N];

void floyd() {
	rep(k, 1, n + 1) rep(i, 1, n + 1) rep(j, 1, n + 1) can[i][j] |= can[i][k] && can[k][j];
}

bool test(int mask, int bit) {
	return mask & (1 << bit);
}

void run() {
	cin >> n >> m;
	rep(i, 0, m) {
		cin >> e[i].a >> e[i].b;
		g[e[i].a].pb({e[i].b, i});
		g[e[i].b].pb({e[i].a, i});
	}
	cin >> p;
	rep(i, 0, p) {
		cin >> x[i] >> y[i];
	}
	
	rep(mask, 0, 1 << m) {
		memset(can, 0, sizeof can);
		rep(i, 0, m) {
			int u = e[i].a;
			int v = e[i].b;
			if (test(mask, i)) {
				swap(u, v);
			}
			can[u][v] |= 1;
		}
		floyd();
		bool ok = 1;
		rep(i, 0, p) {
			ok &= can[x[i]][y[i]];
		}
		if (!ok) continue;
		rep(i, 0, m) {
			if (test(mask, i)) {
				can_left[i] = 1;
			} else {
				can_right[i] = 1;
			}
		}
	}
	
	rep(i, 0, m) {
		if (can_left[i] && can_right[i]) {
			cout << 'B';
		} else if (can_left[i]) {
			cout << 'L';
		} else if (can_right[i]) {
			cout << 'R';
		} else {
			assert(false);
		}
	}
	cout << "\n";
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40