oj.uz

답안 #537537

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
537537 2022-03-15T07:57:41 Z dantoh000 Planine (COCI21_planine) C++14
110 / 110
 353 ms 50792 KB 
#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef pair<ll, ll> ii;
typedef pair<ii, ii> i4;
int n;
ll h;
ii p[1000005];
int Lid[1000005], Rid[1000005];
int ord[1000005];
ll cross(ii x, ii y){
    return x.fi*y.se - x.se*y.fi;
}
bool ccw(int a, int b, int c){
    if (a == -1) return (p[b].se <= p[c].se);
    ii x = ii(p[b].fi - p[a].fi, p[b].se - p[a].se);
    ii y = ii(p[c].fi - p[b].fi, p[c].se - p[b].se);
    return cross(x,y) > 0ll;
}
bool cw(int a, int b, int c){
    if (a == -1) return (p[b].se <= p[c].se);
    ii x = ii(p[b].fi - p[a].fi, p[b].se - p[a].se);
    ii y = ii(p[c].fi - p[b].fi, p[c].se - p[b].se);
    return cross(x,y) < 0ll;
}
ii extrapolate(int a, int b){
    ll dy = p[b].se - p[a].se;
    ll dx = p[b].fi - p[a].fi;
    return ii(p[a].fi*dy + (h-p[a].se)*dx, dy);
}
bool cmp(ii a, ii b){
    //printf("comparing (%lld,%lld) and (%lld,%lld)\n",a.fi,a.se,b.fi,b.se);
    return a.fi*b.se < b.fi*a.se;
}
bool cmp3(ii a, ii b){
    //printf("comparing (%lld,%lld) and (%lld,%lld)\n",a.fi,a.se,b.fi,b.se);
    return  a.fi*b.se > b.fi*a.se;
}
bool cmp2(i4 a, i4 b){
    return cmp(a.se, b.se);
}

vector<pair<ii, ii> > v;
int main(){
    scanf("%d%lld",&n,&h);
    for (int i = 1; i <= n; i++){
        scanf("%lld%lld",&p[i].fi,&p[i].se);
    }
    deque<int> dq;
    dq.push_back(-1);
    for (int i = 1; i <= n; i++){
        while (dq.size() >= 2 && ccw(dq[dq.size()-2], dq[dq.size()-1], i)){
            dq.pop_back();
        }
        Lid[i] = dq.back();
        dq.push_back(i);
    }
    dq.clear();
    dq.push_back(-1);
    for (int i = n; i >= 1; i--){
        while (dq.size() >= 2 && cw(dq[dq.size()-2], dq[dq.size()-1], i)){
            dq.pop_back();
        }
        Rid[i] = dq.back();
        dq.push_back(i);
    }
    for (int i = 3; i < n; i+=2){
        //printf("point %d goes to %d, %d\n",i,Lid[i],Rid[i]);
        ii L = extrapolate(i,Lid[i]);
        ii R = extrapolate(i,Rid[i]);
        v.push_back({L,R});
        //printf("%lld %lld, %lld %lld\n",L[i].fi,L[i].se, R[i].fi, R[i].se);
    }
    sort(v.begin(), v.end(), cmp2);
    ii last = v[0].se;
    int ct = 1;
    for (auto x : v){
        //printf("%lld %lld vs %lld %lld\n",x.fi.fi,x.fi.se, last.fi, last.se);
        if (cmp3(x.fi, last)){
            //printf("setting new R\n");
            last = x.se;
            ct++;
        }
    }
    printf("%d",ct);

}

Compilation message

Main.cpp: In function 'int main()':
Main.cpp:47:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     scanf("%d%lld",&n,&h);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp:49:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         scanf("%lld%lld",&p[i].fi,&p[i].se);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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 24 ms 4844 KB Output is correct
5 Correct 25 ms 4804 KB Output is correct
6 Correct 25 ms 4808 KB Output is correct
7 Correct 265 ms 40312 KB Output is correct
8 Correct 258 ms 40336 KB Output is correct
9 Correct 307 ms 40244 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 1 ms 212 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 0 ms 340 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 24 ms 4844 KB Output is correct
5 Correct 25 ms 4804 KB Output is correct
6 Correct 25 ms 4808 KB Output is correct
7 Correct 265 ms 40312 KB Output is correct
8 Correct 258 ms 40336 KB Output is correct
9 Correct 307 ms 40244 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 1 ms 340 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 340 KB Output is correct
14 Correct 0 ms 340 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 0 ms 340 KB Output is correct
17 Correct 273 ms 50776 KB Output is correct
18 Correct 295 ms 50772 KB Output is correct
19 Correct 28 ms 5920 KB Output is correct
20 Correct 274 ms 50356 KB Output is correct
21 Correct 28 ms 5812 KB Output is correct
22 Correct 295 ms 50792 KB Output is correct
23 Correct 1 ms 340 KB Output is correct
24 Correct 330 ms 50676 KB Output is correct
25 Correct 25 ms 5864 KB Output is correct
26 Correct 353 ms 50776 KB Output is correct
27 Correct 19 ms 3084 KB Output is correct