oj.uz

답안 #538369

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
538369 2022-03-16T16:46:31 Z siewjh Planine (COCI21_planine) C++17
20 / 110
 687 ms 47444 KB 
#include <bits/stdc++.h>
typedef long double ld;
using namespace std;
int nums, h;
const ld error = 1e-9;
struct pt{
    ld x, y;
};
struct hull{
    vector<pt> v;
    ld intersect(pt a, pt b){
        ld m = (b.y - a.y) / (b.x - a.x), c = b.y - b.x * m;
        return (h - c) / m;
    }
    void insert(pt p){
        while (v.size() >= 2 && abs(intersect(p, v.back()) - p.x) >= abs(intersect(p, v[v.size() - 2]) - p.x)) v.pop_back();
        v.push_back(p);
    }
    ld query(pt p){
        while (v.size() >= 2 && abs(intersect(p, v.back()) - p.x) >= abs(intersect(p, v[v.size() - 2]) - p.x)) v.pop_back();
        return intersect(p, v.back());
    }
};
bool cmp(pair<ld, ld> a, pair<ld, ld> b){
    return 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<ld, ld> range[valley];
    hull left;
    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;
    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; ld last_pos = -1e18;
    for (int i = 0; i < valley; i++)
        if (range[i].first > last_pos + error){
            ans++;
            last_pos = range[i].second;
        }
    cout << ans;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 724 KB Output is correct
2 Correct 7 ms 852 KB Output is correct
3 Correct 7 ms 852 KB Output is correct
4 Correct 59 ms 5056 KB Output is correct
5 Correct 64 ms 5004 KB Output is correct
6 Correct 68 ms 5060 KB Output is correct
7 Correct 555 ms 47420 KB Output is correct
8 Correct 631 ms 47436 KB Output is correct
9 Correct 687 ms 47444 KB Output is correct

Subtask #2
0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 340 KB Output is correct
2 Incorrect 2 ms 448 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 724 KB Output is correct
2 Correct 7 ms 852 KB Output is correct
3 Correct 7 ms 852 KB Output is correct
4 Correct 59 ms 5056 KB Output is correct
5 Correct 64 ms 5004 KB Output is correct
6 Correct 68 ms 5060 KB Output is correct
7 Correct 555 ms 47420 KB Output is correct
8 Correct 631 ms 47436 KB Output is correct
9 Correct 687 ms 47444 KB Output is correct
10 Correct 2 ms 340 KB Output is correct
11 Incorrect 2 ms 448 KB Output isn't correct
12 Halted 0 ms 0 KB -