제출 #414150

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
414150		600Mihnea	Cultivation (JOI17_cultivation)	C++17	15 / 100	233 ms	524 KiB

cultivation

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;


const int N = 300 + 7;
const int INF = (int) 1e9 + 7;

int dimx, dimy, n;

struct point {
  int x;
  int y;
};

bool operator < (point a, point b) {
  if (a.x != b.x) return a.x < b.x;
  return a.y < b.y;
}

point v[N];

struct Event {
  int when;
  int l, r;
  int coef;
};

bool operator < (Event a, Event b) {
  if (a.when != b.when) return a.when < b.when;
  return a.coef < b.coef;
}

bool ok(int a, int b, int c, int d) {
  bool ok1 = 0, ok2 = 0;

  vector<Event> events;
  for (int i = 1; i <= n; i++) {
    int x1 = v[i].x - a, x2 = v[i].x + b;
    int y1 = v[i].y - c, y2 = v[i].y + d;

    x1 = max(x1, 1);
    x2 = min(x2, dimx);

    y1 = max(y1, 1);
    y2 = min(y2, dimy);

    events.push_back({x1, y1, y2, +1});
    if (x2 < dimx) {
      events.push_back({x2 + 1, y1, y2, -1});
    }
    ok1 |= (x1 == 1);
    ok2 |= (x2 == dimx);
  }
  sort(events.begin(), events.end());


  if (!ok1 || !ok2) {
    return 0;
  }

  vector<pair<int, int>> intervals;

  for (int step = 0; step < (int) events.size(); step++) {
    auto it = events[step];
    int l = it.l, r = it.r + 1;
    if (it.coef == 1) {
      intervals.push_back({l, r});
    } else {
      pair<int, int> pr = {l, r};
      for (auto &it : intervals) {
        if (it == pr) {
          swap(it, intervals.back());
        }
      }
      assert(!intervals.empty());
      assert(intervals.back() == pr);
      intervals.pop_back();
    }
    if (step + 1 < (int) events.size() && events[step + 1].when == events[step].when) {
      continue;
    }
    sort(intervals.begin(), intervals.end());

    bool good = 1;
    int last = 1;
    for (auto &it : intervals) {
      if (it.first > last) {
        good = 0;
        break;
      }
      last = max(last, it.second);
    }
    good &= (last == dimy + 1);
    if (!good) {
      return 0;
    }
  }
  return 1;
}

vector<int> cover[N];

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

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

  cin >> dimx >> dimy >> n;

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

  if (dimx > 40) {
    return 0;
  }

  int sol = INF;

  for (int a = 0; a <= dimx; a++) {
    for (int b = 0; a + b <= dimx; b++) { /// fix north, south

      for (int i = 1; i <= dimx; i++) {
        cover[i].clear();
      }
      for (int i = 1; i <= n; i++) {
        int l = max(1, v[i].x - a), r = min(dimx, v[i].x + b);
        for (int j = l; j <= r; j++) {
          cover[j].push_back(i);
        }
      }

      bool ok = 1;
      for (int i = 1; i <= dimx; i++) {
        if (cover[i].empty()) {
          ok = 0;
          break;
        }
      }

      if (!ok) {
        continue;
      }

      /// now it's a pretty easy task

      /// For each row I have some restrictions
      int r1 = 0, r2 = 0, rsum = 0;

      for (int i = 1; i <= dimx; i++) {
        vector<int> pts;
        for (auto &j : cover[i]) {
          pts.push_back(v[j].y);
        }

        sort(pts.begin(), pts.end());

        r1 = max(r1, pts[0] - 1);
        r2 = max(r2, dimy - pts.back());

        for (int j = 1; j < (int) pts.size(); j++) {
          rsum = max(rsum, pts[j] - pts[j - 1] - 1);
        }
      }
      rsum = max(rsum, r1 + r2);
      sol = min(sol, a + b + rsum);
    }
  }

  cout << sol << "\n";
  return 0;

/**
  int sol = INF;

  for (int a = 0; a <= dimx; a++) {
    for (int b = 0; b <= dimx; b++) {
      for (int c = 0; c <= dimy; c++) {
        for (int d = 0; d <= dimy; d++) {
          if (a + b + c + d >= sol) continue;
          if (ok(a, b, c, d)) {
            sol = a + b + c + d;
          }
        }
      }
    }
  }
  cout << sol << "\n";
**/
  return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 30
• Subtask 5: 0 / 20
• Subtask 6: 0 / 20