Submission #498510

#	Time	Username	Problem	Language	Result	Execution time	Memory
498510		600Mihnea	Bulldozer (JOI17_bulldozer)	C++17	100 / 100	1965 ms	197628 KiB

bulldozer

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

struct Point {
  ll x;
  ll y;
  ll value;
};

struct R {
  int sgn;
  ll up;
  ll down;
  int i;
  int j;
};

R get(ll x, ll y) {
  R sol;

  sol.sgn = +1;
  if (x < 0 && y < 0) {
    x *= -1;
    y *= -1;
  }
  if (x < 0 || y < 0) {
    sol.sgn = -1;
  }
  sol.up = abs(x);
  sol.down = abs(y);
  return sol;
}

bool operator < (R a, R b) {
  if (a.sgn != b.sgn) {
    return a.sgn < b.sgn;
  }
  if (a.sgn == -1) {
    swap(a, b);
  }
  return a.up * b.down < b.up * a.down;
}

bool initialCmp(Point a, Point b) {
  if (a.y == b.y) {
    return a.x < b.x;
  }
  return a.y < b.y;
}

const int N = 2000 + 7;
int n;
R panta[N][N];
Point points[N];
ll value[N];

void sneakyHack() {
  for (int i = 1; i <= n; i++) {
    swap(points[i].x, points[i].y);
  }
}

int ord[N];
int inv[N];

struct Node {
  ll sol;
  ll sum;
  ll pref;
  ll suf;
};

Node operator + (Node a, Node b) {
  ll sol = max(max(a.sol, b.sol), a.suf + b.pref);
  ll sum = a.sum + b.sum;
  ll pref = max(a.pref, a.sum + b.pref);
  ll suf = max(b.suf, b.sum + a.suf);
  return {sol, sum, pref, suf};
}

Node tree[4 * N];

void build(int v, int tl, int tr) {
  if (tl == tr) {
    tree[v] = {max(value[tl], 0LL), value[tl], max(value[tl], 0LL), max(value[tl], 0LL)};
  } else {
    int tm = (tl + tr) / 2;
    build(2 * v, tl, tm);
    build(2 * v + 1, tm + 1, tr);
    tree[v] = tree[2 * v] + tree[2 * v + 1];
  }
}

void upd(int v, int tl, int tr, int i) {
  if (tr < i || i < tl) {
    return;
  }
  if (tl == tr) {
    tree[v] = {max(value[tl], 0LL), value[tl], max(value[tl], 0LL), max(value[tl], 0LL)};
  } else {
    int tm = (tl + tr) / 2;
    upd(2 * v, tl, tm, i);
    upd(2 * v + 1, tm + 1, tr, i);
    tree[v] = tree[2 * v] + tree[2 * v + 1];
  }
}

int main() {
  bool isHome;

  isHome = true;
  isHome = false;

  if (isHome) {
    freopen ("input", "r", stdin);
  } else {
    ios::sync_with_stdio(0); cin.tie(0);
  }

  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> points[i].x >> points[i].y >> points[i].value;
  }

  ll best = 0;

  for (int iteration = 1; iteration <= 2; iteration++) {
    sneakyHack();
    sort(points + 1, points + n + 1, initialCmp);

    for (int i = 1; i <= n; i++) {
      ord[i] = i;
      inv[i] = i;
      for (int j = i + 1; j <= n; j++) {
        panta[i][j] = get(points[i].x - points[j].x, points[i].y - points[j].y);
        panta[i][j].i = i;
        panta[i][j].j = j;
      }
      value[i] = points[i].value;
    }
    vector<R> all;
    for (int i = 1; i <= n; i++) {
      for (int j = i + 1; j <= n; j++) {
        if (points[i].y != points[j].y) {
          all.push_back(panta[i][j]);
        }
      }
    }
    build(1, 1, n);

    stable_sort(all.begin(), all.end());

    /**

    second : 22 16 10 8 9 11 23 17 15 29
    => 19

    ------------------------------------------

    second : 29 22 16 10 8 9 11 23 17 15
    => 21

    **/

    best = max(best, tree[1].sol);

    /// all[it] < all[it + 1]
    int l = 0;
    while (l < (int) all.size()) {
      int r = l;
      while (r + 1 < (int) all.size() && !(all[r] < all[r + 1])) {
        r++;
      }

      for (int it = l; it <= r; it++) {
        int i = all[it].i;
        int j = all[it].j;
        int pos_i = inv[i];
        int pos_j = inv[j];

        swap(ord[pos_i], ord[pos_j]);
        inv[ord[pos_i]] = pos_i;
        inv[ord[pos_j]] = pos_j;

        swap(value[pos_i], value[pos_j]);
        upd(1, 1, n, pos_i);
        upd(1, 1, n, pos_j);
      }

      best = max(best, tree[1].sol);

      l = r + 1;
    }



  }

  cout << best << "\n";




  return 0;
}

Compilation message (stderr)

bulldozer.cpp: In function 'int main()':
bulldozer.cpp:118:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  118 |     freopen ("input", "r", stdin);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 20 / 20
• Subtask 3: 35 / 35
• Subtask 4: 20 / 20
• Subtask 5: 20 / 20