Submission #410753

#	Time	Username	Problem	Language	Result	Execution time	Memory
410753		600Mihnea	Travelling Merchant (APIO17_merchant)	C++17	100 / 100	124 ms	2172 KiB

merchant

#include <bits/stdc++.h>

using namespace std;

#define int long long
const int N = 100 + 7;
const int K = 1000 + 7;
const int INF = (int) 1e18;
int dist[N][N];
int n, m, k, buy[N][K], sell[N][K], best[N], tab[N][N], sol[N][N];

bool ok(int coef) {
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      sol[i][j] = -INF;
      if (dist[i][j] == INF) continue;
      int mx = tab[i][j];
      sol[i][j] = mx - coef * dist[i][j];
    }
  }
  for (int k = 1; k <= n; k++) {
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= n; j++) {
        sol[i][j] = max(sol[i][j], sol[i][k] + sol[k][j]);
        sol[i][j] = min(sol[i][j], INF);
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (sol[i][j] + sol[j][i] >= 0) {
        return 1;
      }
    }
  }
  return 0;
}

signed main() {
  ios::sync_with_stdio(0); cin.tie(0);

  ///freopen ("input", "r", stdin);

  cin >> n >> m >> k;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= k; j++) {
      cin >> buy[i][j] >> sell[i][j];
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      dist[i][j] = INF;
    }
  }
  for (int i = 1; i <= m; i++) {
    int a, b, c;
    cin >> a >> b >> c;
    dist[a][b] = c;
  }
  for (int k = 1; k <= n; k++) {
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= n; j++) {
        dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      for (int item = 1; item <= k; item++) {
        /// buy at i, sell at j
        if (buy[i][item] != -1 && sell[j][item] != -1) {
          tab[i][j] = max(tab[i][j], sell[j][item] - buy[i][item]);
        }
      }
    }
  }
  int l = 1, r = (int) 1e9, sol = 0;
  while (l <= r) {
    int m = (l + r) / 2;
    if (ok(m)) {
      sol = m;
      l = m + 1;
    } else {
      r = m - 1;
    }
  }
  assert(!ok(sol + 1));
  cout << sol << "\n";
  return 0;
}

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