oj.uz

답안 #538368

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
538368 2022-03-16T16:43:28 Z siewjh Planine (COCI21_planine) C++17
110 / 110
 263 ms 51780 KB 
#include <bits/stdc++.h>
typedef long double ld;
typedef long long ll;
using namespace std;
int nums; ll h;
bool asc;
struct pt{
    ll x, y;
};
struct hull{
    vector<pt> v;
    bool ccw(pt a, pt b, pt c){
        return a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y) > 0;
    }
    bool cw(pt a, pt b, pt c){
        return a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y) < 0;
    }
    void insert(pt p){
      	if (asc) while (v.size() >= 2 && ccw(v[v.size() - 2], v.back(), p)) v.pop_back();
        else while (v.size() >= 2 && cw(v[v.size() - 2], v.back(), p)) v.pop_back();
        v.push_back(p);
    }
    pair<ll, ll> query(pt p){
        if (asc) while (v.size() >= 2 && ccw(v[v.size() - 2], v.back(), p)) v.pop_back();
        else while (v.size() >= 2 && cw(v[v.size() - 2], v.back(), p)) v.pop_back();
        auto a = v.back();
        return {(p.x - a.x) * (h - a.y) + a.x * (p.y - a.y), p.y - a.y};
    }
};
bool cmpfrac(pair<ll, ll> a, pair<ll, ll> b){
    return a.first * b.second < b.first * a.second;
}
bool cmp(pair<pair<ll ,ll>, pair<ll, ll>> a, pair<pair<ll ,ll>, pair<ll, ll>> b){
    return cmpfrac(a.second, b.second);
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> nums >> h;
    pt vec[nums];
    for (int i = 0; i < nums; i++) cin >> vec[i].x >> vec[i].y;
    int valley = (nums - 3) / 2;
    pair<pair<ll, ll>, pair<ll, ll>> range[valley];
    hull left; asc = 1;
    for (int i = 1, j = 0; i < nums - 1; i++){
        if (i % 2) left.insert(vec[i]);
        else {
            range[j].first = left.query(vec[i]);
            j++;
        }
    }
    hull right; asc = 0;
    for (int i = nums - 2, j = valley - 1; i >= 1; i--){
        if (i % 2) right.insert(vec[i]);
        else {
            range[j].second = right.query(vec[i]);
            j--;
        }
    }
    sort(range, range + valley, cmp);
    int ans = 0; pair<ll, ll> last_pos;
    for (int i = 0; i < valley; i++)
        if (i == 0 || cmpfrac(last_pos, range[i].first)){
            ans++;
            last_pos = range[i].second;
        }
    cout << ans;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 852 KB Output is correct
2 Correct 3 ms 852 KB Output is correct
3 Correct 3 ms 852 KB Output is correct
4 Correct 21 ms 5716 KB Output is correct
5 Correct 22 ms 5740 KB Output is correct
6 Correct 26 ms 5712 KB Output is correct
7 Correct 210 ms 51780 KB Output is correct
8 Correct 242 ms 51772 KB Output is correct
9 Correct 241 ms 51772 KB Output is correct

Subtask #2
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 0 ms 212 KB Output is correct

Subtask #3
60.0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 852 KB Output is correct
2 Correct 3 ms 852 KB Output is correct
3 Correct 3 ms 852 KB Output is correct
4 Correct 21 ms 5716 KB Output is correct
5 Correct 22 ms 5740 KB Output is correct
6 Correct 26 ms 5712 KB Output is correct
7 Correct 210 ms 51780 KB Output is correct
8 Correct 242 ms 51772 KB Output is correct
9 Correct 241 ms 51772 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 1 ms 340 KB Output is correct
12 Correct 0 ms 212 KB Output is correct
13 Correct 1 ms 340 KB Output is correct
14 Correct 0 ms 212 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 246 ms 51676 KB Output is correct
18 Correct 255 ms 31696 KB Output is correct
19 Correct 22 ms 3412 KB Output is correct
20 Correct 217 ms 31632 KB Output is correct
21 Correct 22 ms 3452 KB Output is correct
22 Correct 240 ms 31564 KB Output is correct
23 Correct 0 ms 212 KB Output is correct
24 Correct 222 ms 31632 KB Output is correct
25 Correct 21 ms 3412 KB Output is correct
26 Correct 263 ms 31704 KB Output is correct
27 Correct 11 ms 2132 KB Output is correct