Submission #511279

#	Time	Username	Problem	Language	Result	Execution time	Memory
511279		600Mihnea	Salesman (IOI09_salesman)	C++17	42 / 100	3081 ms	37596 KiB

salesman

#include <bits/stdc++.h>


using namespace std;

const int N = (int) 5e5 + 7;
const int INF = (int) 1e9 + 7;
int n;
int add;
int t[N];
int x[N];
int g[N];
int dp[N];
int pref[N];

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

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

  cin >> n;
  {
    int cost1, cost2;
    cin >> cost1 >> cost2;
    add = -(cost1 + cost2);
    cin >> x[0];
    x[n + 1] = x[0];
    t[n + 1] = (int) 5e5 + 3;
  }

  for (int i = 1; i <= n; i++) {
    cin >> t[i] >> x[i] >> g[i];
    g[i] *= 2;
  }

  vector<vector<int>> guys;
  for (int i = 0; i <= n + 1; i++) {
    guys.push_back({t[i], x[i], i});
  }
  sort(guys.begin(), guys.end());
  int current = 0;
  for (int i = 0; i < (int) guys.size(); i++) {
    current += g[guys[i][2]];
    pref[i] = current;
  }
  for (int i = 0; i <= n + 1; i++) {
    x[i] = guys[i][1];
  }
  for (int i = 1; i <= n + 1; i++) {
    dp[i] = -INF;
  }
  {
    int l = 1;
    while (l < (int) guys.size()) {
      int r = l;
      while (r + 1 < (int) guys.size() && guys[r + 1][0] == guys[r][0]) {
        r++;
      }
      int the_best = -INF;
      for (int j = l; j <= r; j++) {
        dp[j] = max(dp[j], the_best + x[j] * add + pref[j]);

        for (int i = 0; i < l; i++) {
          if (x[i] > x[j]) {
            the_best = max(the_best, dp[i] + x[i] * add - pref[j - 1] - 2 * add * x[j]);
          } else {
            the_best = max(the_best, dp[i] - x[i] * add - pref[j - 1]);
          }
        }

      }
      for (int j = l; j <= r; j++) {
        int min_value = -INF;
        for (int i = 0; i < l; i++) {
          for (int k = j; k <= r; k++) {
            if (x[i] > x[k]) {
              min_value = max(min_value, dp[i] + x[i] * add + pref[k]);
            } else {
              min_value = max(min_value, dp[i] - add * x[i] + 2 * x[k] * add + pref[k]);
            }
          }
        }
        min_value = min_value - x[j] * add - pref[j - 1];
        dp[j] = max(dp[j], min_value);
      }
      l = r + 1;
    }
  }
  cout << dp[n + 1] / 2 << "\n";


  return 0;
}

• Subtask 1: 42 / 100