oj.uz

Submission #146581

# Submission time Handle Problem Language Result Execution time Memory
146581 2019-08-24T14:32:48 Z jh05013 None (KOI18_footprint) C++17
55 / 100
 33 ms 5752 KB 
#include <bits/stdc++.h>
#define entire(X) X.begin(),X.end()
#define LAMB [](point const &a, point const &b)->bool
using namespace std; typedef long long ll;
void OJize(){cin.tie(NULL); ios_base::sync_with_stdio(false);}

struct point{
    ll x, y;
    point(ll x, ll y): x{x}, y{y} {}
};
ostream &operator<<(ostream &os, point const &p){
    return os << p.x << ' ' << p.y;
}

// positive -> ccw; negative -> cw; 0 -> collinear
ll ccw(point a, point b, point c){
    return (b.x-a.x)*(c.y-a.y) - (b.y-a.y)*(c.x-a.x);
}

int dp[2][3003][3003];
int prv[2][3003][3003];
vector<point> pnts;

int main(){OJize();
    int n; cin>>n;
    for(int i=0; i<n; i++){
        ll x, y; cin>>x>>y;
        pnts.push_back(point(x, y));
    }
    sort(entire(pnts), LAMB{return a.y < b.y;});
    sort(pnts.begin()+1, pnts.end(), LAMB{return ccw(pnts[0], a, b) > 0;});

    // subtask 1
    if(n > 300){
        cout << n << '\n';
        for(auto &p: pnts) cout<<p<<'\n';
        return 0;
    }

    // base case
    for(int i=1; i<n; i++) dp[0][0][i] = 2; // 0 = heel
    // update
    for(int i=0; i<n; i++) for(int j=i+1; j<n; j++){
        // last edge is i->j
        for(int k=j+1; k<n; k++){
            if(ccw(pnts[j], pnts[k], pnts[0]) == 0) continue;
            ll dr = ccw(pnts[i], pnts[j], pnts[k]);
            if(dr < 0 && dp[0][j][k] <= dp[1][i][j] && dp[1][i][j])
                dp[0][j][k] = dp[1][i][j]+1, prv[0][j][k] = i;
            if(dr > 0 && dp[1][j][k] <= dp[0][i][j] && dp[0][i][j])
                dp[1][j][k] = dp[0][i][j]+1, prv[1][j][k] = i;
        }
    }

    // answer
    int ans = 0, ai = 0, aj = 0;
    for(int i=1; i<n; i++) for(int j=i+1; j<n; j++){
        if(ccw(pnts[i], pnts[j], pnts[0]) <= 0) continue;
        if(ans < dp[0][i][j]) ans = dp[0][i][j], ai = i, aj = j;
    }
    if(ans == 0){cout << 0; return 0;}
    vector<int> trace = {aj, ai};
    while(trace.back()){
        int sz = trace.size();
        trace.push_back(prv[sz%2][trace[sz-1]][trace[sz-2]]);
    }
    reverse(entire(trace));

    cout<<trace.size()<<'\n';
    for(int x: trace) cout<<pnts[x]<<'\n';
}

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 760 KB Output is correct
2 Correct 4 ms 632 KB Output is correct
3 Correct 4 ms 504 KB Output is correct
4 Correct 4 ms 504 KB Output is correct
5 Correct 4 ms 504 KB Output is correct
6 Correct 4 ms 504 KB Output is correct
7 Correct 4 ms 632 KB Output is correct
8 Correct 4 ms 632 KB Output is correct
9 Correct 4 ms 632 KB Output is correct
10 Correct 4 ms 632 KB Output is correct
11 Correct 6 ms 632 KB Output is correct
12 Correct 4 ms 632 KB Output is correct
13 Correct 4 ms 504 KB Output is correct
14 Correct 4 ms 632 KB Output is correct
15 Correct 4 ms 632 KB Output is correct

Subtask #2
12.0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 376 KB Output is correct
2 Correct 2 ms 404 KB Output is correct
3 Correct 2 ms 376 KB Output is correct
4 Correct 2 ms 508 KB Output is correct
5 Correct 2 ms 504 KB Output is correct
6 Correct 2 ms 376 KB Output is correct
7 Correct 2 ms 376 KB Output is correct
8 Correct 2 ms 376 KB Output is correct
9 Correct 2 ms 376 KB Output is correct
10 Correct 2 ms 504 KB Output is correct
11 Correct 2 ms 504 KB Output is correct
12 Correct 2 ms 376 KB Output is correct
13 Correct 2 ms 376 KB Output is correct
14 Correct 2 ms 376 KB Output is correct
15 Correct 2 ms 376 KB Output is correct
16 Correct 2 ms 376 KB Output is correct
17 Correct 2 ms 376 KB Output is correct
18 Correct 2 ms 376 KB Output is correct
19 Correct 2 ms 504 KB Output is correct
20 Correct 2 ms 376 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 376 KB Output is correct
2 Correct 2 ms 404 KB Output is correct
3 Correct 2 ms 376 KB Output is correct
4 Correct 2 ms 508 KB Output is correct
5 Correct 2 ms 504 KB Output is correct
6 Correct 2 ms 376 KB Output is correct
7 Correct 2 ms 376 KB Output is correct
8 Correct 2 ms 376 KB Output is correct
9 Correct 2 ms 376 KB Output is correct
10 Correct 2 ms 504 KB Output is correct
11 Correct 2 ms 504 KB Output is correct
12 Correct 2 ms 376 KB Output is correct
13 Correct 2 ms 376 KB Output is correct
14 Correct 2 ms 376 KB Output is correct
15 Correct 2 ms 376 KB Output is correct
16 Correct 2 ms 376 KB Output is correct
17 Correct 2 ms 376 KB Output is correct
18 Correct 2 ms 376 KB Output is correct
19 Correct 2 ms 504 KB Output is correct
20 Correct 2 ms 376 KB Output is correct
21 Correct 23 ms 5212 KB Output is correct
22 Correct 25 ms 5240 KB Output is correct
23 Correct 23 ms 5240 KB Output is correct
24 Correct 29 ms 5752 KB Output is correct
25 Correct 29 ms 5628 KB Output is correct
26 Correct 29 ms 5724 KB Output is correct
27 Correct 29 ms 5624 KB Output is correct
28 Correct 29 ms 5656 KB Output is correct
29 Correct 29 ms 5672 KB Output is correct
30 Correct 31 ms 5624 KB Output is correct
31 Correct 33 ms 5624 KB Output is correct
32 Correct 31 ms 5752 KB Output is correct
33 Correct 20 ms 3192 KB Output is correct
34 Correct 20 ms 3192 KB Output is correct
35 Correct 20 ms 3192 KB Output is correct

Subtask #4
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 760 KB Output is correct
2 Correct 4 ms 632 KB Output is correct
3 Correct 4 ms 504 KB Output is correct
4 Correct 4 ms 504 KB Output is correct
5 Correct 4 ms 504 KB Output is correct
6 Correct 4 ms 504 KB Output is correct
7 Correct 4 ms 632 KB Output is correct
8 Correct 4 ms 632 KB Output is correct
9 Correct 4 ms 632 KB Output is correct
10 Correct 4 ms 632 KB Output is correct
11 Correct 6 ms 632 KB Output is correct
12 Correct 4 ms 632 KB Output is correct
13 Correct 4 ms 504 KB Output is correct
14 Correct 4 ms 632 KB Output is correct
15 Correct 4 ms 632 KB Output is correct
16 Correct 2 ms 376 KB Output is correct
17 Correct 2 ms 404 KB Output is correct
18 Correct 2 ms 376 KB Output is correct
19 Correct 2 ms 508 KB Output is correct
20 Correct 2 ms 504 KB Output is correct
21 Correct 2 ms 376 KB Output is correct
22 Correct 2 ms 376 KB Output is correct
23 Correct 2 ms 376 KB Output is correct
24 Correct 2 ms 376 KB Output is correct
25 Correct 2 ms 504 KB Output is correct
26 Correct 2 ms 504 KB Output is correct
27 Correct 2 ms 376 KB Output is correct
28 Correct 2 ms 376 KB Output is correct
29 Correct 2 ms 376 KB Output is correct
30 Correct 2 ms 376 KB Output is correct
31 Correct 2 ms 376 KB Output is correct
32 Correct 2 ms 376 KB Output is correct
33 Correct 2 ms 376 KB Output is correct
34 Correct 2 ms 504 KB Output is correct
35 Correct 2 ms 376 KB Output is correct
36 Correct 23 ms 5212 KB Output is correct
37 Correct 25 ms 5240 KB Output is correct
38 Correct 23 ms 5240 KB Output is correct
39 Correct 29 ms 5752 KB Output is correct
40 Correct 29 ms 5628 KB Output is correct
41 Correct 29 ms 5724 KB Output is correct
42 Correct 29 ms 5624 KB Output is correct
43 Correct 29 ms 5656 KB Output is correct
44 Correct 29 ms 5672 KB Output is correct
45 Correct 31 ms 5624 KB Output is correct
46 Correct 33 ms 5624 KB Output is correct
47 Correct 31 ms 5752 KB Output is correct
48 Correct 20 ms 3192 KB Output is correct
49 Correct 20 ms 3192 KB Output is correct
50 Correct 20 ms 3192 KB Output is correct
51 Correct 4 ms 636 KB Output is correct
52 Correct 4 ms 504 KB Output is correct
53 Correct 5 ms 504 KB Output is correct
54 Incorrect 4 ms 504 KB Output isn't correct
55 Halted 0 ms 0 KB -