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Submission #79564

# Submission time Handle Problem Language Result Execution time Memory
79564 2018-10-15T03:12:48 Z Flying_dragon_02 Network (BOI15_net) C++14
100 / 100
 665 ms 52028 KB 
#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back
#define mp make_pair

typedef pair<int, int> ii;

const int N = 5e5 + 5;

int n, dp[N];
bool vis[N];
vector<int> graph[N];
vector<int> ans;

void dfs(int u, int p) {
    vis[u] = 1;
    int cnt = 0;
    for(int i = 0; i < graph[u].size(); i++) {
        int v = graph[u][i];
        if(!vis[v] && v != p) {
            dfs(v, u);
            cnt++;
        }
    }
    if(!cnt)
        ans.pb(u);
}

int main() {
    cin.tie(0), ios::sync_with_stdio(0);
    cin >> n;
    for(int i = 1; i <= n - 1; i++) {
        int u, v;
        cin >> u >> v;
        graph[u].pb(v);
        graph[v].pb(u);
    }
    int cen;
    for(int i = 1; i <= n; i++) {
        if(graph[i].size() > 1)
            cen = i;
    }
    dfs(cen, cen);
    if(ans.size() % 2 == 0) {
        cout << ans.size() / 2 << "\n";
        for(int i = 0; i < ans.size() / 2; i++) {
            cout << ans[i] << " " << ans[i + ans.size() / 2] << "\n";
        }
    }
    else {
        cout << ans.size() / 2 + 1 << "\n";
        cout << ans[ans.size() / 2] << " " << cen << "\n";
        for(int i = 0; i < ans.size() / 2; i++) {
            cout << ans[i] << " " << ans[i + ans.size() / 2 + 1] << "\n";
        }
    }
}

Compilation message

net.cpp: In function 'void dfs(int, int)':
net.cpp:22:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < graph[u].size(); i++) {
                    ~~^~~~~~~~~~~~~~~~~
net.cpp: In function 'int main()':
net.cpp:50:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < ans.size() / 2; i++) {
                        ~~^~~~~~~~~~~~~~~~
net.cpp:57:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < ans.size() / 2; i++) {
                        ~~^~~~~~~~~~~~~~~~
net.cpp:56:54: warning: 'cen' may be used uninitialized in this function [-Wmaybe-uninitialized]
         cout << ans[ans.size() / 2] << " " << cen << "\n";
                                                      ^~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12152 KB Output is correct
2 Correct 11 ms 12268 KB Output is correct
3 Correct 12 ms 12268 KB Output is correct
4 Correct 12 ms 12268 KB Output is correct
5 Correct 12 ms 12268 KB Output is correct
6 Correct 12 ms 12288 KB Output is correct
7 Correct 12 ms 12288 KB Output is correct
8 Correct 12 ms 12288 KB Output is correct
9 Correct 12 ms 12288 KB Output is correct
10 Correct 12 ms 12288 KB Output is correct
11 Correct 12 ms 12288 KB Output is correct
12 Correct 12 ms 12288 KB Output is correct
13 Correct 12 ms 12288 KB Output is correct
14 Correct 12 ms 12380 KB Output is correct
15 Correct 13 ms 12380 KB Output is correct
16 Correct 13 ms 12380 KB Output is correct
17 Correct 13 ms 12380 KB Output is correct
18 Correct 12 ms 12380 KB Output is correct
19 Correct 12 ms 12384 KB Output is correct
20 Correct 11 ms 12384 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12152 KB Output is correct
2 Correct 11 ms 12268 KB Output is correct
3 Correct 12 ms 12268 KB Output is correct
4 Correct 12 ms 12268 KB Output is correct
5 Correct 12 ms 12268 KB Output is correct
6 Correct 12 ms 12288 KB Output is correct
7 Correct 12 ms 12288 KB Output is correct
8 Correct 12 ms 12288 KB Output is correct
9 Correct 12 ms 12288 KB Output is correct
10 Correct 12 ms 12288 KB Output is correct
11 Correct 12 ms 12288 KB Output is correct
12 Correct 12 ms 12288 KB Output is correct
13 Correct 12 ms 12288 KB Output is correct
14 Correct 12 ms 12380 KB Output is correct
15 Correct 13 ms 12380 KB Output is correct
16 Correct 13 ms 12380 KB Output is correct
17 Correct 13 ms 12380 KB Output is correct
18 Correct 12 ms 12380 KB Output is correct
19 Correct 12 ms 12384 KB Output is correct
20 Correct 11 ms 12384 KB Output is correct
21 Correct 11 ms 12384 KB Output is correct
22 Correct 12 ms 12396 KB Output is correct
23 Correct 13 ms 12396 KB Output is correct
24 Correct 12 ms 12412 KB Output is correct
25 Correct 13 ms 12456 KB Output is correct
26 Correct 13 ms 12456 KB Output is correct
27 Correct 17 ms 12456 KB Output is correct
28 Correct 13 ms 12456 KB Output is correct
29 Correct 13 ms 12456 KB Output is correct
30 Correct 12 ms 12456 KB Output is correct
31 Correct 14 ms 12456 KB Output is correct
32 Correct 12 ms 12456 KB Output is correct
33 Correct 12 ms 12456 KB Output is correct
34 Correct 12 ms 12456 KB Output is correct
35 Correct 16 ms 12456 KB Output is correct
36 Correct 12 ms 12456 KB Output is correct
37 Correct 12 ms 12460 KB Output is correct
38 Correct 17 ms 12460 KB Output is correct
39 Correct 12 ms 12460 KB Output is correct
40 Correct 12 ms 12460 KB Output is correct
41 Correct 12 ms 12460 KB Output is correct
42 Correct 12 ms 12460 KB Output is correct
43 Correct 13 ms 12460 KB Output is correct
44 Correct 12 ms 12460 KB Output is correct
45 Correct 12 ms 12460 KB Output is correct
46 Correct 12 ms 12460 KB Output is correct
47 Correct 12 ms 12460 KB Output is correct
48 Correct 11 ms 12460 KB Output is correct
49 Correct 13 ms 12464 KB Output is correct
50 Correct 12 ms 12464 KB Output is correct
51 Correct 11 ms 12464 KB Output is correct
52 Correct 13 ms 12464 KB Output is correct
53 Correct 14 ms 12464 KB Output is correct
54 Correct 13 ms 12464 KB Output is correct
55 Correct 14 ms 12464 KB Output is correct
56 Correct 11 ms 12464 KB Output is correct
57 Correct 11 ms 12464 KB Output is correct
58 Correct 12 ms 12464 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 12152 KB Output is correct
2 Correct 11 ms 12268 KB Output is correct
3 Correct 12 ms 12268 KB Output is correct
4 Correct 12 ms 12268 KB Output is correct
5 Correct 12 ms 12268 KB Output is correct
6 Correct 12 ms 12288 KB Output is correct
7 Correct 12 ms 12288 KB Output is correct
8 Correct 12 ms 12288 KB Output is correct
9 Correct 12 ms 12288 KB Output is correct
10 Correct 12 ms 12288 KB Output is correct
11 Correct 12 ms 12288 KB Output is correct
12 Correct 12 ms 12288 KB Output is correct
13 Correct 12 ms 12288 KB Output is correct
14 Correct 12 ms 12380 KB Output is correct
15 Correct 13 ms 12380 KB Output is correct
16 Correct 13 ms 12380 KB Output is correct
17 Correct 13 ms 12380 KB Output is correct
18 Correct 12 ms 12380 KB Output is correct
19 Correct 12 ms 12384 KB Output is correct
20 Correct 11 ms 12384 KB Output is correct
21 Correct 11 ms 12384 KB Output is correct
22 Correct 12 ms 12396 KB Output is correct
23 Correct 13 ms 12396 KB Output is correct
24 Correct 12 ms 12412 KB Output is correct
25 Correct 13 ms 12456 KB Output is correct
26 Correct 13 ms 12456 KB Output is correct
27 Correct 17 ms 12456 KB Output is correct
28 Correct 13 ms 12456 KB Output is correct
29 Correct 13 ms 12456 KB Output is correct
30 Correct 12 ms 12456 KB Output is correct
31 Correct 14 ms 12456 KB Output is correct
32 Correct 12 ms 12456 KB Output is correct
33 Correct 12 ms 12456 KB Output is correct
34 Correct 12 ms 12456 KB Output is correct
35 Correct 16 ms 12456 KB Output is correct
36 Correct 12 ms 12456 KB Output is correct
37 Correct 12 ms 12460 KB Output is correct
38 Correct 17 ms 12460 KB Output is correct
39 Correct 12 ms 12460 KB Output is correct
40 Correct 12 ms 12460 KB Output is correct
41 Correct 12 ms 12460 KB Output is correct
42 Correct 12 ms 12460 KB Output is correct
43 Correct 13 ms 12460 KB Output is correct
44 Correct 12 ms 12460 KB Output is correct
45 Correct 12 ms 12460 KB Output is correct
46 Correct 12 ms 12460 KB Output is correct
47 Correct 12 ms 12460 KB Output is correct
48 Correct 11 ms 12460 KB Output is correct
49 Correct 13 ms 12464 KB Output is correct
50 Correct 12 ms 12464 KB Output is correct
51 Correct 11 ms 12464 KB Output is correct
52 Correct 13 ms 12464 KB Output is correct
53 Correct 14 ms 12464 KB Output is correct
54 Correct 13 ms 12464 KB Output is correct
55 Correct 14 ms 12464 KB Output is correct
56 Correct 11 ms 12464 KB Output is correct
57 Correct 11 ms 12464 KB Output is correct
58 Correct 12 ms 12464 KB Output is correct
59 Correct 437 ms 30860 KB Output is correct
60 Correct 578 ms 32928 KB Output is correct
61 Correct 13 ms 32928 KB Output is correct
62 Correct 12 ms 32928 KB Output is correct
63 Correct 384 ms 32928 KB Output is correct
64 Correct 14 ms 32928 KB Output is correct
65 Correct 25 ms 32928 KB Output is correct
66 Correct 160 ms 32928 KB Output is correct
67 Correct 665 ms 52028 KB Output is correct
68 Correct 647 ms 52028 KB Output is correct
69 Correct 22 ms 52028 KB Output is correct
70 Correct 110 ms 52028 KB Output is correct
71 Correct 367 ms 52028 KB Output is correct
72 Correct 375 ms 52028 KB Output is correct
73 Correct 121 ms 52028 KB Output is correct
74 Correct 546 ms 52028 KB Output is correct
75 Correct 69 ms 52028 KB Output is correct
76 Correct 365 ms 52028 KB Output is correct
77 Correct 369 ms 52028 KB Output is correct
78 Correct 46 ms 52028 KB Output is correct
79 Correct 652 ms 52028 KB Output is correct
80 Correct 14 ms 52028 KB Output is correct
81 Correct 120 ms 52028 KB Output is correct
82 Correct 444 ms 52028 KB Output is correct
83 Correct 533 ms 52028 KB Output is correct
84 Correct 563 ms 52028 KB Output is correct
85 Correct 495 ms 52028 KB Output is correct
86 Correct 482 ms 52028 KB Output is correct
87 Correct 545 ms 52028 KB Output is correct