oj.uz

Submission #146656

# Submission time Handle Problem Language Result Execution time Memory
146656 2019-08-25T02:26:19 Z jh05013 None (KOI18_footprint) C++17
100 / 100
 1273 ms 111096 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;});

    // 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++)
            if(!i || ccw(pnts[0], pnts[i], pnts[j])) bef.push_back(i);
        for(int k=j+1; k<n; k++)
            if(ccw(pnts[0], pnts[j], pnts[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(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(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:47:22: 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:56:22: 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 1027 ms 98444 KB Output is correct
2 Correct 1063 ms 100876 KB Output is correct
3 Correct 1035 ms 99520 KB Output is correct
4 Correct 1054 ms 100940 KB Output is correct
5 Correct 1065 ms 100072 KB Output is correct
6 Correct 1064 ms 101112 KB Output is correct
7 Correct 1047 ms 100536 KB Output is correct
8 Correct 1056 ms 101112 KB Output is correct
9 Correct 1079 ms 101368 KB Output is correct
10 Correct 1063 ms 101388 KB Output is correct
11 Correct 1073 ms 101148 KB Output is correct
12 Correct 1070 ms 101688 KB Output is correct
13 Correct 1096 ms 103104 KB Output is correct
14 Correct 1069 ms 101240 KB Output is correct
15 Correct 1091 ms 99680 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 504 KB Output is correct
5 Correct 2 ms 504 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 376 KB Output is correct
9 Correct 2 ms 504 KB Output is correct
10 Correct 3 ms 552 KB Output is correct
11 Correct 3 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 632 KB Output is correct
15 Correct 2 ms 508 KB Output is correct
16 Correct 2 ms 376 KB Output is correct
17 Correct 2 ms 380 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 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 504 KB Output is correct
5 Correct 2 ms 504 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 376 KB Output is correct
9 Correct 2 ms 504 KB Output is correct
10 Correct 3 ms 552 KB Output is correct
11 Correct 3 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 632 KB Output is correct
15 Correct 2 ms 508 KB Output is correct
16 Correct 2 ms 376 KB Output is correct
17 Correct 2 ms 380 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 504 KB Output is correct
21 Correct 13 ms 5368 KB Output is correct
22 Correct 14 ms 5484 KB Output is correct
23 Correct 13 ms 5368 KB Output is correct
24 Correct 15 ms 5880 KB Output is correct
25 Correct 15 ms 5880 KB Output is correct
26 Correct 15 ms 5880 KB Output is correct
27 Correct 14 ms 5752 KB Output is correct
28 Correct 15 ms 5752 KB Output is correct
29 Correct 15 ms 5752 KB Output is correct
30 Correct 15 ms 5880 KB Output is correct
31 Correct 16 ms 5880 KB Output is correct
32 Correct 15 ms 5884 KB Output is correct
33 Correct 11 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
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 1027 ms 98444 KB Output is correct
2 Correct 1063 ms 100876 KB Output is correct
3 Correct 1035 ms 99520 KB Output is correct
4 Correct 1054 ms 100940 KB Output is correct
5 Correct 1065 ms 100072 KB Output is correct
6 Correct 1064 ms 101112 KB Output is correct
7 Correct 1047 ms 100536 KB Output is correct
8 Correct 1056 ms 101112 KB Output is correct
9 Correct 1079 ms 101368 KB Output is correct
10 Correct 1063 ms 101388 KB Output is correct
11 Correct 1073 ms 101148 KB Output is correct
12 Correct 1070 ms 101688 KB Output is correct
13 Correct 1096 ms 103104 KB Output is correct
14 Correct 1069 ms 101240 KB Output is correct
15 Correct 1091 ms 99680 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 504 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 376 KB Output is correct
24 Correct 2 ms 504 KB Output is correct
25 Correct 3 ms 552 KB Output is correct
26 Correct 3 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 632 KB Output is correct
30 Correct 2 ms 508 KB Output is correct
31 Correct 2 ms 376 KB Output is correct
32 Correct 2 ms 380 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 504 KB Output is correct
36 Correct 13 ms 5368 KB Output is correct
37 Correct 14 ms 5484 KB Output is correct
38 Correct 13 ms 5368 KB Output is correct
39 Correct 15 ms 5880 KB Output is correct
40 Correct 15 ms 5880 KB Output is correct
41 Correct 15 ms 5880 KB Output is correct
42 Correct 14 ms 5752 KB Output is correct
43 Correct 15 ms 5752 KB Output is correct
44 Correct 15 ms 5752 KB Output is correct
45 Correct 15 ms 5880 KB Output is correct
46 Correct 16 ms 5880 KB Output is correct
47 Correct 15 ms 5884 KB Output is correct
48 Correct 11 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 1057 ms 100884 KB Output is correct
52 Correct 1067 ms 101216 KB Output is correct
53 Correct 1099 ms 102776 KB Output is correct
54 Correct 1254 ms 110984 KB Output is correct
55 Correct 1244 ms 110912 KB Output is correct
56 Correct 1255 ms 111056 KB Output is correct
57 Correct 1245 ms 110616 KB Output is correct
58 Correct 1256 ms 110820 KB Output is correct
59 Correct 1245 ms 110708 KB Output is correct
60 Correct 1273 ms 111004 KB Output is correct
61 Correct 1244 ms 111096 KB Output is correct
62 Correct 1243 ms 110956 KB Output is correct
63 Correct 574 ms 110968 KB Output is correct
64 Correct 571 ms 110968 KB Output is correct
65 Correct 568 ms 110840 KB Output is correct
66 Correct 865 ms 110852 KB Output is correct
67 Correct 855 ms 110668 KB Output is correct
68 Correct 906 ms 110716 KB Output is correct