oj.uz

Submission #588500

# Submission time Handle Problem Language Result Execution time Memory
588500 2022-07-03T12:03:12 Z MilosMilutinovic Planine (COCI21_planine) C++14
110 / 110
 244 ms 54596 KB 
/**
 *    author:  wxhtzdy
 *    created: 03.07.2022 13:33:18
**/
#include <bits/stdc++.h>

using namespace std;

string to_string(string s) {
  return '"' + s + '"';
}
string to_string(const char* s) {
  return to_string((string) s);
}
string to_string(bool b) {
  return (b ? "true" : "false");
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

struct Frac {
  long long p, q;
};

bool operator < (Frac a, Frac b) {
  return a.p * b.q < b.p * a.q;
}

struct Point {
  int x, y;
};

int orientation(Point a, Point b, Point c) {
  long long prod = (b.y - a.y) * 1LL * (c.x - b.x)
                   - (b.x - a.x) * 1LL * (c.y - b.y);
  return (prod == 0 ? 0 : (prod > 0 ? 1 : -1));
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);  
  int n, h;
  cin >> n >> h;
  vector<Point> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i].x >> a[i].y;
  }
  vector<Point> L(n);
  {
    vector<Point> hull(1, a[0]);
    for (int i = 1; i < n; i++) {
      while ((int) hull.size() > 1 && orientation(hull.rbegin()[1], hull.rbegin()[0], a[i]) == -1) {
        hull.pop_back();  
      }
      L[i] = hull.back();
      hull.push_back(a[i]);  
    }
  }
  vector<Point> R(n);
  {
    vector<Point> hull(1, a[n - 1]);
    for (int i = n - 2; i >= 0; i--) {
      while ((int) hull.size() > 1 && orientation(a[i], hull.rbegin()[0], hull.rbegin()[1]) == -1) {
        hull.pop_back();  
      }
      R[i] = hull.back();
      hull.push_back(a[i]);  
    }
  }                         
  for (int i = 2; i < n - 1; i += 2) {
    debug(i, L[i].x, L[i].y);
    debug(i, R[i].x, R[i].y);
  }
  vector<pair<Frac, Frac>> ev;
  for (int i = 2; i < n - 1; i += 2) {
    Frac fL, fR;
    fL.p = a[i].x * 1LL * (L[i].y - a[i].y) + (h - a[i].y) * 1LL * (L[i].x - a[i].x);
    fL.q = L[i].y - a[i].y;
    fR.p = a[i].x * 1LL * (R[i].y - a[i].y) + (h - a[i].y) * 1LL * (R[i].x - a[i].x);
    fR.q = R[i].y - a[i].y;
    ev.emplace_back(fL, fR);
  }
  sort(ev.begin(), ev.end(), [&](pair<Frac, Frac> a, pair<Frac, Frac> b) {
    return a.second < b.second;
  });
  Frac lst;
  int ans = 0;
  for (int i = 0; i < (int) ev.size(); i++) {
    if (i == 0 || lst < ev[i].first) {
      ans += 1;
      lst = ev[i].second;      
    }
  }
  cout << ans << '\n';                 
  return 0;
}

Compilation message

Main.cpp: In function 'int main()':
Main.cpp:45:20: warning: statement has no effect [-Wunused-value]
   45 | #define debug(...) 42
      |                    ^~
Main.cpp:98:5: note: in expansion of macro 'debug'
   98 |     debug(i, L[i].x, L[i].y);
      |     ^~~~~
Main.cpp:45:20: warning: statement has no effect [-Wunused-value]
   45 | #define debug(...) 42
      |                    ^~
Main.cpp:99:5: note: in expansion of macro 'debug'
   99 |     debug(i, R[i].x, R[i].y);
      |     ^~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 980 KB Output is correct
2 Correct 3 ms 968 KB Output is correct
3 Correct 3 ms 980 KB Output is correct
4 Correct 19 ms 5824 KB Output is correct
5 Correct 20 ms 6068 KB Output is correct
6 Correct 22 ms 6208 KB Output is correct
7 Correct 231 ms 50468 KB Output is correct
8 Correct 219 ms 52412 KB Output is correct
9 Correct 219 ms 54320 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 1 ms 212 KB Output is correct

Subtask #3
60.0 / 60.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 980 KB Output is correct
2 Correct 3 ms 968 KB Output is correct
3 Correct 3 ms 980 KB Output is correct
4 Correct 19 ms 5824 KB Output is correct
5 Correct 20 ms 6068 KB Output is correct
6 Correct 22 ms 6208 KB Output is correct
7 Correct 231 ms 50468 KB Output is correct
8 Correct 219 ms 52412 KB Output is correct
9 Correct 219 ms 54320 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 1 ms 332 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 340 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 195 ms 51484 KB Output is correct
18 Correct 212 ms 51216 KB Output is correct
19 Correct 20 ms 5856 KB Output is correct
20 Correct 202 ms 50424 KB Output is correct
21 Correct 22 ms 5828 KB Output is correct
22 Correct 212 ms 54200 KB Output is correct
23 Correct 0 ms 212 KB Output is correct
24 Correct 211 ms 53304 KB Output is correct
25 Correct 21 ms 5992 KB Output is correct
26 Correct 244 ms 54596 KB Output is correct
27 Correct 12 ms 3148 KB Output is correct