Submission #1365825

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Source Code Expand

#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

template<int MOD>
struct ModInt {
	static const int Mod = MOD;
	unsigned x;
	ModInt() : x(0) { }
	ModInt(signed sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; }
	ModInt(signed long long sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; }
	int get() const { return (int)x; }

	ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; }

	ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
};
typedef ModInt<1000000007> mint;

int main() {
	int N; int M;
	while (~scanf("%d%d", &N, &M)) {
		vector<int> graph(N);
		rep(i, M) {
			int u; int v;
			scanf("%d%d", &u, &v), -- u, -- v;
			graph[u] |= 1 << v;
		}
		vector<int> popcount(1 << N);
		rep(i, 1 << N) rep(j, N)
			popcount[i] += i >> j & 1;
		vector<mint> pow2s(N + 1);
		pow2s[0] = 1;
		rer(i, 1, N)
			pow2s[i] = pow2s[i - 1] * 2;
		//後ろから考える
		vector<mint> dp(1 << N);
		dp[0] = 1;
		rep(S, 1 << N) {
			mint x = dp[S];
			if (x.x == 0) continue;
			int rem = (1 << N) - 1 - S;
			for (int T = rem; T > 0; (-- T) &= rem) {
				if ((T & 3) == 3) continue;
				int U = rem - T;
				mint y = x;
				rep(i, N) if (S >> i & 1)
					y *= pow2s[popcount[graph[i] & T]];
				rep(i, N) if (U >> i & 1)
					y *= pow2s[popcount[graph[i] & T]] - 1;
				dp[S | T] += y;
			}
		}
		mint ans = dp.back();
		printf("%d\n", ans.get());
	}
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:36:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d%d", &u, &v), -- u, -- v;
                                     ^

Judge Result