oj.uz

Submission #146654

# Submission time Handle Problem Language Result Execution time Memory
146654 2019-08-25T01:43:06 Z jh05013 None (KOI18_footprint) C++17
55 / 100
 17 ms 5880 KB 
#include <bits/stdc++.h>
#define entire(X) X.begin(),X.end()
#define LAMB [](point const &a, point const &b)->bool
#define LAMBI [&j](int const &a, int 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 j=1; j<n-1; j++){
        vector<int> bef, aft;
        for(int i=0; i<j; i++) bef.push_back(i);
        for(int k=j+1; k<n; k++) aft.push_back(k);
        sort(entire(bef), LAMBI{return ccw(pnts[j], pnts[a], pnts[b]) > 0;});
        sort(entire(aft), LAMBI{return ccw(pnts[j], pnts[a], pnts[b]) > 0;});
        int ptr = 0, maxd = 0, pid = 0;
        for(int k: aft){
            while(ptr<bef.size() && ccw(pnts[j], pnts[k], pnts[bef[ptr]]) > 0){
                int i = bef[ptr++];
                if(i && ccw(pnts[0], pnts[i], pnts[j]) == 0) continue;
                if(dp[0][i][j] && maxd <= dp[0][i][j])
                    maxd = dp[0][i][j]+1, pid = i;
            }
            dp[1][j][k] = maxd, prv[1][j][k] = pid;
        }
        reverse(entire(bef)), reverse(entire(aft));
        ptr = maxd = pid = 0;
        for(int k: aft){
            while(ptr<bef.size() && ccw(pnts[j], pnts[k], pnts[bef[ptr]]) < 0){
                int i = bef[ptr++];
                if(i && ccw(pnts[0], pnts[i], pnts[j]) == 0) continue;
                if(dp[1][i][j] && maxd <= dp[1][i][j])
                    maxd = dp[1][i][j]+1, pid = i;
            }
            dp[0][j][k] = maxd, prv[0][j][k] = pid;
        }
    }

    // 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';
}

Compilation message

footprint.cpp: In function 'int main()':
footprint.cpp:52:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while(ptr<bef.size() && ccw(pnts[j], pnts[k], pnts[bef[ptr]]) > 0){
                   ~~~^~~~~~~~~~~
footprint.cpp:63:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while(ptr<bef.size() && ccw(pnts[j], pnts[k], pnts[bef[ptr]]) < 0){
                   ~~~^~~~~~~~~~~

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 632 KB Output is correct
2 Correct 4 ms 632 KB Output is correct
3 Correct 5 ms 632 KB Output is correct
4 Correct 4 ms 632 KB Output is correct
5 Correct 4 ms 632 KB Output is correct
6 Correct 4 ms 504 KB Output is correct
7 Correct 4 ms 504 KB Output is correct
8 Correct 4 ms 504 KB Output is correct
9 Correct 4 ms 504 KB Output is correct
10 Correct 5 ms 632 KB Output is correct
11 Correct 5 ms 728 KB Output is correct
12 Correct 4 ms 632 KB Output is correct
13 Correct 4 ms 632 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 376 KB Output is correct
3 Correct 2 ms 376 KB Output is correct
4 Correct 2 ms 476 KB Output is correct
5 Correct 2 ms 496 KB Output is correct
6 Correct 2 ms 504 KB Output is correct
7 Correct 2 ms 504 KB Output is correct
8 Correct 2 ms 504 KB Output is correct
9 Correct 2 ms 504 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 504 KB Output is correct
13 Correct 2 ms 504 KB Output is correct
14 Correct 2 ms 504 KB Output is correct
15 Correct 2 ms 504 KB Output is correct
16 Correct 2 ms 544 KB Output is correct
17 Correct 2 ms 504 KB Output is correct
18 Correct 2 ms 504 KB Output is correct
19 Correct 2 ms 504 KB Output is correct
20 Correct 2 ms 504 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 376 KB Output is correct
3 Correct 2 ms 376 KB Output is correct
4 Correct 2 ms 476 KB Output is correct
5 Correct 2 ms 496 KB Output is correct
6 Correct 2 ms 504 KB Output is correct
7 Correct 2 ms 504 KB Output is correct
8 Correct 2 ms 504 KB Output is correct
9 Correct 2 ms 504 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 504 KB Output is correct
13 Correct 2 ms 504 KB Output is correct
14 Correct 2 ms 504 KB Output is correct
15 Correct 2 ms 504 KB Output is correct
16 Correct 2 ms 544 KB Output is correct
17 Correct 2 ms 504 KB Output is correct
18 Correct 2 ms 504 KB Output is correct
19 Correct 2 ms 504 KB Output is correct
20 Correct 2 ms 504 KB Output is correct
21 Correct 13 ms 5368 KB Output is correct
22 Correct 14 ms 5496 KB Output is correct
23 Correct 14 ms 5368 KB Output is correct
24 Correct 16 ms 5808 KB Output is correct
25 Correct 15 ms 5880 KB Output is correct
26 Correct 15 ms 5880 KB Output is correct
27 Correct 15 ms 5752 KB Output is correct
28 Correct 15 ms 5752 KB Output is correct
29 Correct 17 ms 5880 KB Output is correct
30 Correct 15 ms 5880 KB Output is correct
31 Correct 15 ms 5880 KB Output is correct
32 Correct 16 ms 5880 KB Output is correct
33 Correct 10 ms 5880 KB Output is correct
34 Correct 10 ms 5880 KB Output is correct
35 Correct 10 ms 5880 KB Output is correct

Subtask #4
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 632 KB Output is correct
2 Correct 4 ms 632 KB Output is correct
3 Correct 5 ms 632 KB Output is correct
4 Correct 4 ms 632 KB Output is correct
5 Correct 4 ms 632 KB Output is correct
6 Correct 4 ms 504 KB Output is correct
7 Correct 4 ms 504 KB Output is correct
8 Correct 4 ms 504 KB Output is correct
9 Correct 4 ms 504 KB Output is correct
10 Correct 5 ms 632 KB Output is correct
11 Correct 5 ms 728 KB Output is correct
12 Correct 4 ms 632 KB Output is correct
13 Correct 4 ms 632 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 376 KB Output is correct
18 Correct 2 ms 376 KB Output is correct
19 Correct 2 ms 476 KB Output is correct
20 Correct 2 ms 496 KB Output is correct
21 Correct 2 ms 504 KB Output is correct
22 Correct 2 ms 504 KB Output is correct
23 Correct 2 ms 504 KB Output is correct
24 Correct 2 ms 504 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 504 KB Output is correct
28 Correct 2 ms 504 KB Output is correct
29 Correct 2 ms 504 KB Output is correct
30 Correct 2 ms 504 KB Output is correct
31 Correct 2 ms 544 KB Output is correct
32 Correct 2 ms 504 KB Output is correct
33 Correct 2 ms 504 KB Output is correct
34 Correct 2 ms 504 KB Output is correct
35 Correct 2 ms 504 KB Output is correct
36 Correct 13 ms 5368 KB Output is correct
37 Correct 14 ms 5496 KB Output is correct
38 Correct 14 ms 5368 KB Output is correct
39 Correct 16 ms 5808 KB Output is correct
40 Correct 15 ms 5880 KB Output is correct
41 Correct 15 ms 5880 KB Output is correct
42 Correct 15 ms 5752 KB Output is correct
43 Correct 15 ms 5752 KB Output is correct
44 Correct 17 ms 5880 KB Output is correct
45 Correct 15 ms 5880 KB Output is correct
46 Correct 15 ms 5880 KB Output is correct
47 Correct 16 ms 5880 KB Output is correct
48 Correct 10 ms 5880 KB Output is correct
49 Correct 10 ms 5880 KB Output is correct
50 Correct 10 ms 5880 KB Output is correct
51 Correct 4 ms 524 KB Output is correct
52 Correct 4 ms 504 KB Output is correct
53 Correct 4 ms 504 KB Output is correct
54 Incorrect 4 ms 632 KB Output isn't correct
55 Halted 0 ms 0 KB -