Submission #858586

#	Time	Username	Problem	Language	Result	Execution time	Memory
858586		NK_	Plus Minus (BOI17_plusminus)	C++17	100 / 100	66 ms	12592 KiB

plusminus

// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
 
using namespace std;
 
#define nl '\n'
#define pb push_back
#define pf push_front
 
#define mp make_pair
#define f first
#define s second
#define sz(x) int(x.size())
 
template<class T> using V = vector<T>;
using pi = pair<int, int>;
using vi = V<int>;
using vpi = V<pi>;
 
using ll = long long;
using pl = pair<ll, ll>;
using vpl = V<pl>;
using vl = V<ll>;
 
using db = long double;
 
template<class T> using pq = priority_queue<T, V<T>, greater<T>>;
 
const int MOD = 1e9 + 7;
const ll INFL = ll(1e17);
const int LG = 18;

int main() {
	cin.tie(0)->sync_with_stdio(0);

	int N, M, K; cin >> N >> M >> K;

	V<array<int, 3>> A(K);
	for(int i = 0; i < K; i++) {
		char ch; int r, c; cin >> ch >> r >> c; --r, --c;
		A[i] = {r, c, ch == '+'};
	}

	auto POW = [&](ll a, ll p) {
		if (p < 0) return 0LL;
		ll ans = 1;
		for(; p; p /= 2, a = (a * a) % MOD) if (p & 1) ans = (ans * a) % MOD;
		return ans;
	};

	int ways = 0;
	ll ans = 0;
	for(int i = 0; i < 2; i++) {
		unordered_set<int> R; unordered_map<int, int> PR;
		int res = 0;
		for(auto& v : A) {
			auto [r, c, x] = v;
			int p = (r ^ c) & 1;
			int pr = p ^ x;

			// cout << r << " " << c << " => " << x << " " << pr << endl;
			if (R.count(r)) {
				// cout << pr << " " << PR[r] << endl;
				if (pr != PR[r]) res = -1;
			} else R.insert(r), PR[r] = pr;

			swap(v[0], v[1]);
		}

		if (res != -1) {
			ways++;
			ans += POW(2, N - sz(R));
			// cout << sz(R) << endl;
		}

		swap(N, M);
	}

	if (ways == 2) ans--;
	if (K == 0) ans--;

	cout << (ans + MOD) % MOD << nl;

	exit(0-0);
} 	 

• Subtask 1: 12 / 12
• Subtask 2: 42 / 42
• Subtask 3: 46 / 46