Submission #106229

#	Time	Username	Problem	Language	Result	Execution time	Memory
106229		polyfish	Travelling Merchant (APIO17_merchant)	C++14	100 / 100	111 ms	3260 KiB

merchant

//Pantyhose(black) + glasses = infinity
 
#include <bits/stdc++.h>
using namespace std;
 
#define debug(x) cerr << #x << " = " << x << '\n';
#define BP() cerr << "OK!\n";
#define PR(A, n) {cerr << #A << " = "; for (int64_t _=1; _<=n; ++_) cerr << A[_] << ' '; cerr << '\n';}
#define PR0(A, n) {cerr << #A << " = "; for (int64_t _=0; _<n; ++_) cerr << A[_] << ' '; cerr << '\n';}
#define FILE_NAME "merchant"
 
const int64_t MAX_N = 102;
const int64_t MAX_K = 1002;
const int64_t INF = 1e9+1e8;
const int64_t _EPS = 1e-8;
 
struct edge {
	int64_t u, v;
	int64_t w;
 
	edge() {}
 
	edge(int64_t u, int64_t v, int64_t w): u(u), v(v), w(w) {}
};
 
int64_t n, m, k, b[MAX_N][MAX_K], s[MAX_N][MAX_K], c[MAX_N][MAX_N], mx[MAX_N][MAX_N];
int64_t topo[MAX_N], timer;
bool visited[MAX_N];
vector<edge> g[MAX_N]; 
int64_t d[MAX_N];
 
void read_input() {
	cin >> n >> m >> k;
 
	for (int64_t i=1; i<=n; ++i) {
		for (int64_t j=1; j<=k; ++j)
			cin >> b[i][j] >> s[i][j];
	}
}
 
void floyd() {
	for (int64_t i=1; i<=n; ++i) {
		for (int64_t j=1; j<=n; ++j)
			c[i][j] = INF;
	}
 
	for (int64_t i=1; i<=n; ++i)
		c[i][i] = 0;
 
	for (int64_t i=1; i<=m; ++i) {
		int64_t u, v;
		cin >> u >> v;
		cin >> c[u][v];
	}
 
	for (int64_t k=1; k<=n; ++k) {
		for (int64_t i=1; i<=n; ++i) {
			for (int64_t j=1; j<=n; ++j)
				c[i][j] = min(c[i][j], c[i][k] + c[k][j]);
		}
	}
 
	// debug(c[4][1]);
}
 
void init() {
	for (int64_t i=1; i<=n; ++i) {
		for (int64_t j=1; j<=n; ++j) {
			mx[i][j] = -INF;
 
			for (int64_t t=1; t<=k; ++t) {
				if (b[i][t]!=-1 && s[j][t]!=-1)
					mx[i][j] = max(mx[i][j], -b[i][t] + s[j][t]);
			}
		}
	}
 
	// debug(mx[1][4]);
}
 
bool relax(edge e) {
	if (abs(d[e.v] - d[e.u] - e.w)>_EPS && d[e.v] > d[e.u] + e.w) {
		d[e.v] = d[e.u] + e.w;
		return true;
	}
 
	return false;
}
 
int detect_zero_cycle(int u) {
	visited[u] = true;

	for (auto e : g[u]) {
		if (abs(d[e.v] - d[e.u] - e.w)<=_EPS && !visited[e.v])
			detect_zero_cycle(e.v);
	}

	topo[u] = ++timer;
}

bool check_negative_cycle(int64_t x) {
	vector<edge> E;
 
	for (int64_t i=1; i<=n; ++i) {
		g[i].clear();

		for (int64_t j=1; j<=n; ++j) {
			// if (i==4 && j==1)
			// 	debug(x*c[i][j] - max((int64_t)0, mx[i][j]));
			if (i!=j) {
				E.push_back(edge(i, j, x*c[i][j] - max((int64_t)0, mx[i][j])));
				g[i].push_back(edge(i, j, x*c[i][j] - max((int64_t)0, mx[i][j])));
			}
		}
	}
 
	memset(d, 0, sizeof(d));
 
	for (int64_t i=0; i<=n; ++i) {
		if (i==n)
			return true;
 
		bool stop = true;
 
		for (auto e : E) {
			if (relax(e))
				stop = false;
		}
 
		if (stop)
			break;
	}

	// debug(detect_zero_cycle(1, 1));

	memset(visited, false, sizeof(visited));
	timer = 0;

	for (int i=1; i<=n; ++i) {
		if (!visited[i])
			detect_zero_cycle(i);
	}
 
	for (int u=1; u<=n; ++u) {
		for (auto e : g[u]) {
			if (abs(d[e.v] - d[e.u] - e.w)<=_EPS && topo[u]<topo[e.v])
				return true;
		}
	}

	return false;
}
 
int64_t bisect() {
	int64_t l = 0, r = INF;

	for (int64_t mid=(l+r)/2; mid!=l && r!=mid; mid=(l+r)/2) {
		if (check_negative_cycle(mid))
			l = mid;
		else
			r = mid;
	}

	for (int64_t i=r; i>=l; --i) {
		if (check_negative_cycle(i))
			return i;
	}
 
 	return 0;
}
 
int main() {
	ios::sync_with_stdio(0); cin.tie(0);
 
	read_input();
	floyd();
	init();
	// debug(check_negative_cycle(2));
	cout << int64_t(bisect());
}

Compilation message (stderr)

merchant.cpp: In function 'int detect_zero_cycle(int)':
merchant.cpp:99:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^

• Subtask 1: 12 / 12
• Subtask 2: 21 / 21
• Subtask 3: 33 / 33
• Subtask 4: 34 / 34