oj.uz

Submission #126230

# Submission time Handle Problem Language Result Execution time Memory
126230 2019-07-07T09:37:29 Z Vardanyan Network (BOI15_net) C++14
100 / 100
 1241 ms 70272 KB 
#include <bits/stdc++.h>
using namespace std;
const int N = 500*1000+5;
vector<int> g[N];
bool used[N];
int timer, tin[N], fup[N];
bool f = false;
void dfs (int v, int p = -1) {
	used[v] = true;
	tin[v] = fup[v] = timer++;
	for (size_t i=0; i<g[v].size(); ++i) {
		int to = g[v][i];
		if (to == p)  continue;
		if (used[to])
			fup[v] = min (fup[v], tin[to]);
		else {
			dfs (to, v);
			fup[v] = min (fup[v], fup[to]);
			if (fup[to] > tin[v])
				f = true;
		}
	}
}
int n;
void find_bridges() {
	timer = 0;
	f = false;
	memset(tin,0,sizeof(tin));
	memset(fup,0,sizeof(fup));
	for (int i=1; i<=n; ++i)
		used[i] = false;
	for (int i=1; i<=n; ++i)
		if (!used[i])
			dfs (i);
}
int main(){
    ios_base::sync_with_stdio(false);
    cin>>n;
    for(int i = 1;i<=n-1;i++){
        int x,y;
        cin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    vector<int> lf;
    for(int i = 1;i<=n;i++){
        if(g[i].size() == 1) lf.push_back(i);
    }
    /*
    cout<<(lf.size()+1)/2<<endl;
    for(int i = 0;i<lf.size()-1;i+=2){
        cout<<lf[i]<< " "<<lf[i+1]<<endl;
    }
    if(lf.size()%2){
        cout<<lf[lf.size()-1]<<" "<<lf[lf.size()-2]<<endl;
    }*/
    int tim = 50;
    while(tim--){
        random_shuffle(lf.begin(),lf.end());
        //cout<<(lf.size()+1)/2<<endl;
        for(int i = 0;i<lf.size()-1;i+=2){
            //cout<<lf[i]<< " "<<lf[i+1]<<endl;
            g[lf[i]].push_back(lf[i+1]);
            g[lf[i+1]].push_back(lf[i]);
        }
        if(lf.size()%2){
        //    cout<<lf[lf.size()-1]<<" "<<lf[lf.size()-2]<<endl;
            g[lf[lf.size()-1]].push_back(lf[lf.size()-2]);
            g[lf[lf.size()-2]].push_back(lf[lf.size()-1]);
        }
        find_bridges();
        if(!f){
            cout<<(lf.size()+1)/2<<endl;
            for(int i = 0;i<lf.size()-1;i+=2){
                cout<<lf[i]<< " "<<lf[i+1]<<endl;
            }
            if(lf.size()%2){
                cout<<lf[lf.size()-1]<<" "<<lf[lf.size()-2]<<endl;
            }
            return 0;
        }
         for(int i = 0;i<lf.size()-1;i+=2){
            //cout<<lf[i]<< " "<<lf[i+1]<<endl;
            g[lf[i]].pop_back();
            g[lf[i+1]].pop_back();
        }
        if(lf.size()%2){
        //    cout<<lf[lf.size()-1]<<" "<<lf[lf.size()-2]<<endl;
            g[lf[lf.size()-1]].pop_back();
            g[lf[lf.size()-2]].pop_back();
        }
    }
    return 0;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:61:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0;i<lf.size()-1;i+=2){
                       ~^~~~~~~~~~~~
net.cpp:74:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i = 0;i<lf.size()-1;i+=2){
                           ~^~~~~~~~~~~~
net.cpp:82:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for(int i = 0;i<lf.size()-1;i+=2){
                        ~^~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 16012 KB Output is correct
2 Correct 21 ms 15992 KB Output is correct
3 Correct 18 ms 15992 KB Output is correct
4 Correct 16 ms 15992 KB Output is correct
5 Correct 16 ms 15992 KB Output is correct
6 Correct 16 ms 15992 KB Output is correct
7 Correct 16 ms 15992 KB Output is correct
8 Correct 16 ms 15992 KB Output is correct
9 Correct 17 ms 16040 KB Output is correct
10 Correct 16 ms 16020 KB Output is correct
11 Correct 16 ms 16028 KB Output is correct
12 Correct 16 ms 15992 KB Output is correct
13 Correct 19 ms 16068 KB Output is correct
14 Correct 17 ms 15992 KB Output is correct
15 Correct 17 ms 15992 KB Output is correct
16 Correct 16 ms 15992 KB Output is correct
17 Correct 17 ms 15992 KB Output is correct
18 Correct 16 ms 15992 KB Output is correct
19 Correct 16 ms 15992 KB Output is correct
20 Correct 16 ms 15992 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 16012 KB Output is correct
2 Correct 21 ms 15992 KB Output is correct
3 Correct 18 ms 15992 KB Output is correct
4 Correct 16 ms 15992 KB Output is correct
5 Correct 16 ms 15992 KB Output is correct
6 Correct 16 ms 15992 KB Output is correct
7 Correct 16 ms 15992 KB Output is correct
8 Correct 16 ms 15992 KB Output is correct
9 Correct 17 ms 16040 KB Output is correct
10 Correct 16 ms 16020 KB Output is correct
11 Correct 16 ms 16028 KB Output is correct
12 Correct 16 ms 15992 KB Output is correct
13 Correct 19 ms 16068 KB Output is correct
14 Correct 17 ms 15992 KB Output is correct
15 Correct 17 ms 15992 KB Output is correct
16 Correct 16 ms 15992 KB Output is correct
17 Correct 17 ms 15992 KB Output is correct
18 Correct 16 ms 15992 KB Output is correct
19 Correct 16 ms 15992 KB Output is correct
20 Correct 16 ms 15992 KB Output is correct
21 Correct 19 ms 15992 KB Output is correct
22 Correct 20 ms 16120 KB Output is correct
23 Correct 23 ms 16092 KB Output is correct
24 Correct 20 ms 16120 KB Output is correct
25 Correct 19 ms 16148 KB Output is correct
26 Correct 19 ms 16120 KB Output is correct
27 Correct 19 ms 16120 KB Output is correct
28 Correct 19 ms 16120 KB Output is correct
29 Correct 18 ms 16248 KB Output is correct
30 Correct 17 ms 15992 KB Output is correct
31 Correct 19 ms 16124 KB Output is correct
32 Correct 16 ms 15992 KB Output is correct
33 Correct 19 ms 15992 KB Output is correct
34 Correct 16 ms 15992 KB Output is correct
35 Correct 16 ms 15992 KB Output is correct
36 Correct 16 ms 16020 KB Output is correct
37 Correct 16 ms 15992 KB Output is correct
38 Correct 16 ms 15992 KB Output is correct
39 Correct 16 ms 15992 KB Output is correct
40 Correct 16 ms 15992 KB Output is correct
41 Correct 16 ms 16120 KB Output is correct
42 Correct 16 ms 15992 KB Output is correct
43 Correct 18 ms 16120 KB Output is correct
44 Correct 16 ms 16120 KB Output is correct
45 Correct 16 ms 15992 KB Output is correct
46 Correct 17 ms 16120 KB Output is correct
47 Correct 16 ms 15996 KB Output is correct
48 Correct 16 ms 15992 KB Output is correct
49 Correct 18 ms 16120 KB Output is correct
50 Correct 16 ms 15992 KB Output is correct
51 Correct 16 ms 15992 KB Output is correct
52 Correct 16 ms 16040 KB Output is correct
53 Correct 17 ms 16024 KB Output is correct
54 Correct 16 ms 15996 KB Output is correct
55 Correct 16 ms 15992 KB Output is correct
56 Correct 16 ms 15992 KB Output is correct
57 Correct 17 ms 15992 KB Output is correct
58 Correct 19 ms 16120 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 16012 KB Output is correct
2 Correct 21 ms 15992 KB Output is correct
3 Correct 18 ms 15992 KB Output is correct
4 Correct 16 ms 15992 KB Output is correct
5 Correct 16 ms 15992 KB Output is correct
6 Correct 16 ms 15992 KB Output is correct
7 Correct 16 ms 15992 KB Output is correct
8 Correct 16 ms 15992 KB Output is correct
9 Correct 17 ms 16040 KB Output is correct
10 Correct 16 ms 16020 KB Output is correct
11 Correct 16 ms 16028 KB Output is correct
12 Correct 16 ms 15992 KB Output is correct
13 Correct 19 ms 16068 KB Output is correct
14 Correct 17 ms 15992 KB Output is correct
15 Correct 17 ms 15992 KB Output is correct
16 Correct 16 ms 15992 KB Output is correct
17 Correct 17 ms 15992 KB Output is correct
18 Correct 16 ms 15992 KB Output is correct
19 Correct 16 ms 15992 KB Output is correct
20 Correct 16 ms 15992 KB Output is correct
21 Correct 19 ms 15992 KB Output is correct
22 Correct 20 ms 16120 KB Output is correct
23 Correct 23 ms 16092 KB Output is correct
24 Correct 20 ms 16120 KB Output is correct
25 Correct 19 ms 16148 KB Output is correct
26 Correct 19 ms 16120 KB Output is correct
27 Correct 19 ms 16120 KB Output is correct
28 Correct 19 ms 16120 KB Output is correct
29 Correct 18 ms 16248 KB Output is correct
30 Correct 17 ms 15992 KB Output is correct
31 Correct 19 ms 16124 KB Output is correct
32 Correct 16 ms 15992 KB Output is correct
33 Correct 19 ms 15992 KB Output is correct
34 Correct 16 ms 15992 KB Output is correct
35 Correct 16 ms 15992 KB Output is correct
36 Correct 16 ms 16020 KB Output is correct
37 Correct 16 ms 15992 KB Output is correct
38 Correct 16 ms 15992 KB Output is correct
39 Correct 16 ms 15992 KB Output is correct
40 Correct 16 ms 15992 KB Output is correct
41 Correct 16 ms 16120 KB Output is correct
42 Correct 16 ms 15992 KB Output is correct
43 Correct 18 ms 16120 KB Output is correct
44 Correct 16 ms 16120 KB Output is correct
45 Correct 16 ms 15992 KB Output is correct
46 Correct 17 ms 16120 KB Output is correct
47 Correct 16 ms 15996 KB Output is correct
48 Correct 16 ms 15992 KB Output is correct
49 Correct 18 ms 16120 KB Output is correct
50 Correct 16 ms 15992 KB Output is correct
51 Correct 16 ms 15992 KB Output is correct
52 Correct 16 ms 16040 KB Output is correct
53 Correct 17 ms 16024 KB Output is correct
54 Correct 16 ms 15996 KB Output is correct
55 Correct 16 ms 15992 KB Output is correct
56 Correct 16 ms 15992 KB Output is correct
57 Correct 17 ms 15992 KB Output is correct
58 Correct 19 ms 16120 KB Output is correct
59 Correct 1014 ms 55456 KB Output is correct
60 Correct 1167 ms 58748 KB Output is correct
61 Correct 16 ms 15992 KB Output is correct
62 Correct 19 ms 15992 KB Output is correct
63 Correct 1006 ms 52276 KB Output is correct
64 Correct 18 ms 16376 KB Output is correct
65 Correct 32 ms 17912 KB Output is correct
66 Correct 183 ms 29792 KB Output is correct
67 Correct 624 ms 70272 KB Output is correct
68 Correct 662 ms 55408 KB Output is correct
69 Correct 45 ms 16888 KB Output is correct
70 Correct 337 ms 25448 KB Output is correct
71 Correct 1223 ms 46620 KB Output is correct
72 Correct 1169 ms 45240 KB Output is correct
73 Correct 253 ms 27172 KB Output is correct
74 Correct 1039 ms 56228 KB Output is correct
75 Correct 122 ms 19320 KB Output is correct
76 Correct 1219 ms 46048 KB Output is correct
77 Correct 1241 ms 46260 KB Output is correct
78 Correct 68 ms 20472 KB Output is correct
79 Correct 608 ms 63552 KB Output is correct
80 Correct 23 ms 16248 KB Output is correct
81 Correct 351 ms 26608 KB Output is correct
82 Correct 1119 ms 47252 KB Output is correct
83 Correct 1022 ms 56428 KB Output is correct
84 Correct 1006 ms 56400 KB Output is correct
85 Correct 1046 ms 56348 KB Output is correct
86 Correct 1161 ms 58680 KB Output is correct
87 Correct 1163 ms 58660 KB Output is correct