oj.uz

Submission #234640

# Submission time Handle Problem Language Result Execution time Memory
234640 2020-05-24T23:10:59 Z knon0501 None (KOI18_footprint) C++14
14 / 100
 22 ms 760 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define x first
#define y second
typedef pair<ll,ll> pp;
pp a[3005];
int dp[3005];
pp p[3005];
int ccw(pp q,pp w,pp e){
    ll s=(w.x-q.x)*(e.y-w.y)-(w.y-q.y)*(e.x-w.x);
    if(s>0)return 1;
    if(s==0)return 0;
    if(s<0)return -1;
}
int n;
ll dist(pp q,pp w){
    return (q.x-w.x)*(q.x-w.x)+(q.y-w.y)*(q.y-w.y);
}
int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    cin>>n;
    int i;
    int k=1;
    for(i=1 ; i<=n ; i++){
        cin>>a[i].x>>a[i].y;
        if(a[i].y<a[k].y)k=i;
    }

    swap(a[k],a[1]);
    sort(a+2,a+n+1,[&](pp q,pp w){ll s=ccw(a[1],q,w);
        if(s==0)return dist(a[1],q)<dist(a[1],w);
        else return s>0;});
   // for(i=1 ; i<=n ; i++)cout<<a[i].x<<" "<<a[i].y<<endl;
    k=0;
    for(i=2 ; i<=n ; i++)dp[i]=1;
    for(i=2 ; i<=n ; i++){

        int t=i+1;
        if(dp[i]>dp[k])k=i;
        for(int j=i+2 ; j<=n ; j++){
            if(ccw(a[1],a[t],a[j])!=0 && ccw(a[1],a[t],a[i])!=0 && ccw(a[i],a[t],a[j])<0){
                if(dp[i]+1>dp[j]){
                    dp[j]=dp[i]+1;
                    p[j]={i,t};
                }
            }
            else if(ccw(a[i],a[t],a[j])>0)t=j;
        }
    }

    if(dp[k]<=1){
        cout<<0;
        return 0;
    }
    vector<pp> b;
    cout<<2*dp[k]<<"\n";
    cout<<a[1].x<<" "<<a[1].y<<"\n";

    while(k>0){
        b.push_back(a[k]);
        if(p[k].second>0)
            b.push_back(a[p[k].second]);
        k=p[k].first;
    }
    reverse(b.begin(),b.end());
    for(auto i: b)cout<<i.x<<" "<<i.y<<"\n";
    return 0;
}

Compilation message

footprint.cpp: In function 'int ccw(pp, pp, pp)':
footprint.cpp:15:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 640 KB Output is correct
2 Correct 22 ms 640 KB Output is correct
3 Correct 20 ms 640 KB Output is correct
4 Correct 20 ms 640 KB Output is correct
5 Correct 20 ms 640 KB Output is correct
6 Correct 20 ms 640 KB Output is correct
7 Correct 20 ms 640 KB Output is correct
8 Correct 20 ms 640 KB Output is correct
9 Correct 22 ms 640 KB Output is correct
10 Correct 20 ms 640 KB Output is correct
11 Correct 20 ms 640 KB Output is correct
12 Correct 21 ms 640 KB Output is correct
13 Correct 21 ms 640 KB Output is correct
14 Correct 20 ms 640 KB Output is correct
15 Correct 20 ms 760 KB Output is correct

Subtask #2
0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Incorrect 4 ms 384 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #3
0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Incorrect 4 ms 384 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #4
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 640 KB Output is correct
2 Correct 22 ms 640 KB Output is correct
3 Correct 20 ms 640 KB Output is correct
4 Correct 20 ms 640 KB Output is correct
5 Correct 20 ms 640 KB Output is correct
6 Correct 20 ms 640 KB Output is correct
7 Correct 20 ms 640 KB Output is correct
8 Correct 20 ms 640 KB Output is correct
9 Correct 22 ms 640 KB Output is correct
10 Correct 20 ms 640 KB Output is correct
11 Correct 20 ms 640 KB Output is correct
12 Correct 21 ms 640 KB Output is correct
13 Correct 21 ms 640 KB Output is correct
14 Correct 20 ms 640 KB Output is correct
15 Correct 20 ms 760 KB Output is correct
16 Correct 4 ms 384 KB Output is correct
17 Correct 4 ms 384 KB Output is correct
18 Correct 5 ms 384 KB Output is correct
19 Incorrect 4 ms 384 KB Output isn't correct
20 Halted 0 ms 0 KB -