Submission #79592

# Submission time Handle Problem Language Result Execution time Memory
79592 2018-10-15T04:18:19 Z EntityIT Network (BOI15_net) C++14
100 / 100
977 ms 80828 KB
#include<bits/stdc++.h>

using namespace std;

#define pb push_back
#define fi first
#define se second
typedef pair<int, int> ii;

const int N = 5e5 + 5;
int n, child[N], nLeaf, cur, tmp, pter[N];
vector<int> gr[N], vec[N];

void prep (int u, int p) {
    for (int v : gr[u]) if (v != p) {
        prep(v, u);
        child[u] += child[v];
    }
    child[u] += (gr[u].size() == 1);
}

int findCentroid (int u, int p) {
    for (int v : gr[u]) if (v != p) {
        if (child[v] >= (nLeaf + 1) / 2 ) return findCentroid(v, u);
    }
    return u;
}

void dfs (int u, int p) {
    for (int v : gr[u]) if (v != p) dfs(v, u);
    if (gr[u].size() == 1) vec[cur].pb(u);
}

int main () {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n;
    for (int _ = 1; _ < n; ++_) {
        int u, v; cin >> u >> v;
        gr[u].pb(v); gr[v].pb(u);
    }
    int root;
    for (int i = 1; i <= n; ++i) if (gr[i].size() ) root = i;

    for (int u = 1; u <= n; ++u) nLeaf += (gr[u].size() == 1);
    cout << (nLeaf + 1) / 2 << '\n';
    prep(root, root);
    int cen = findCentroid(root, root);

    for (int u : gr[cen]) cur ++, dfs(u, cen);

    priority_queue<ii> pq;
    for (int i = 1; i <= cur; ++i) {
        pq.push(ii(vec[i].size() - pter[i], i) );
    }

    while (pq.size() > 1) {
        ii tmp1 = pq.top(); pq.pop();
        ii tmp2 = pq.top(); pq.pop();

        cout << vec[tmp1.se][ pter[tmp1.se] ] << ' ' << vec[tmp2.se][ pter[tmp2.se] ] << '\n';
        pter[tmp1.se] ++; pter[tmp2.se] ++;
        if (pter[tmp1.se] < vec[tmp1.se].size() ) pq.push(ii(vec[tmp1.se].size() - pter[tmp1.se], tmp1.se) );
        if (pter[tmp2.se] < vec[tmp2.se].size() ) pq.push(ii(vec[tmp2.se].size() - pter[tmp2.se], tmp2.se) );
    }

    if (pq.size() ) {
        int u = vec[pq.top().se][ pter[pq.top().se] ];
        for (int v = 1; v <= n; ++v) if (gr[v].size() == 1 && v != u) { cout << v << ' ' << u << '\n'; break; }
    }

    return 0;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:62:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (pter[tmp1.se] < vec[tmp1.se].size() ) pq.push(ii(vec[tmp1.se].size() - pter[tmp1.se], tmp1.se) );
             ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
net.cpp:63:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (pter[tmp2.se] < vec[tmp2.se].size() ) pq.push(ii(vec[tmp2.se].size() - pter[tmp2.se], tmp2.se) );
             ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
net.cpp:47:38: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int cen = findCentroid(root, root);
                                      ^
# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 24 ms 23860 KB Output is correct
3 Correct 28 ms 24000 KB Output is correct
4 Correct 24 ms 24204 KB Output is correct
5 Correct 23 ms 24204 KB Output is correct
6 Correct 23 ms 24204 KB Output is correct
7 Correct 23 ms 24204 KB Output is correct
8 Correct 25 ms 24204 KB Output is correct
9 Correct 29 ms 24204 KB Output is correct
10 Correct 23 ms 24204 KB Output is correct
11 Correct 27 ms 24204 KB Output is correct
12 Correct 24 ms 24204 KB Output is correct
13 Correct 25 ms 24204 KB Output is correct
14 Correct 23 ms 24204 KB Output is correct
15 Correct 24 ms 24204 KB Output is correct
16 Correct 23 ms 24204 KB Output is correct
17 Correct 25 ms 24204 KB Output is correct
18 Correct 29 ms 24204 KB Output is correct
19 Correct 23 ms 24204 KB Output is correct
20 Correct 26 ms 24204 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 24 ms 23860 KB Output is correct
3 Correct 28 ms 24000 KB Output is correct
4 Correct 24 ms 24204 KB Output is correct
5 Correct 23 ms 24204 KB Output is correct
6 Correct 23 ms 24204 KB Output is correct
7 Correct 23 ms 24204 KB Output is correct
8 Correct 25 ms 24204 KB Output is correct
9 Correct 29 ms 24204 KB Output is correct
10 Correct 23 ms 24204 KB Output is correct
11 Correct 27 ms 24204 KB Output is correct
12 Correct 24 ms 24204 KB Output is correct
13 Correct 25 ms 24204 KB Output is correct
14 Correct 23 ms 24204 KB Output is correct
15 Correct 24 ms 24204 KB Output is correct
16 Correct 23 ms 24204 KB Output is correct
17 Correct 25 ms 24204 KB Output is correct
18 Correct 29 ms 24204 KB Output is correct
19 Correct 23 ms 24204 KB Output is correct
20 Correct 26 ms 24204 KB Output is correct
21 Correct 23 ms 24204 KB Output is correct
22 Correct 24 ms 24204 KB Output is correct
23 Correct 24 ms 24204 KB Output is correct
24 Correct 24 ms 24340 KB Output is correct
25 Correct 24 ms 24340 KB Output is correct
26 Correct 24 ms 24340 KB Output is correct
27 Correct 24 ms 24340 KB Output is correct
28 Correct 24 ms 24340 KB Output is correct
29 Correct 23 ms 24340 KB Output is correct
30 Correct 24 ms 24340 KB Output is correct
31 Correct 24 ms 24340 KB Output is correct
32 Correct 23 ms 24340 KB Output is correct
33 Correct 23 ms 24340 KB Output is correct
34 Correct 23 ms 24340 KB Output is correct
35 Correct 23 ms 24340 KB Output is correct
36 Correct 23 ms 24340 KB Output is correct
37 Correct 24 ms 24340 KB Output is correct
38 Correct 23 ms 24340 KB Output is correct
39 Correct 25 ms 24340 KB Output is correct
40 Correct 23 ms 24340 KB Output is correct
41 Correct 23 ms 24340 KB Output is correct
42 Correct 28 ms 24340 KB Output is correct
43 Correct 23 ms 24340 KB Output is correct
44 Correct 25 ms 24340 KB Output is correct
45 Correct 24 ms 24340 KB Output is correct
46 Correct 24 ms 24340 KB Output is correct
47 Correct 23 ms 24340 KB Output is correct
48 Correct 24 ms 24340 KB Output is correct
49 Correct 23 ms 24340 KB Output is correct
50 Correct 22 ms 24340 KB Output is correct
51 Correct 25 ms 24340 KB Output is correct
52 Correct 22 ms 24340 KB Output is correct
53 Correct 23 ms 24340 KB Output is correct
54 Correct 28 ms 24340 KB Output is correct
55 Correct 22 ms 24340 KB Output is correct
56 Correct 27 ms 24340 KB Output is correct
57 Correct 23 ms 24340 KB Output is correct
58 Correct 26 ms 24340 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 24 ms 23860 KB Output is correct
3 Correct 28 ms 24000 KB Output is correct
4 Correct 24 ms 24204 KB Output is correct
5 Correct 23 ms 24204 KB Output is correct
6 Correct 23 ms 24204 KB Output is correct
7 Correct 23 ms 24204 KB Output is correct
8 Correct 25 ms 24204 KB Output is correct
9 Correct 29 ms 24204 KB Output is correct
10 Correct 23 ms 24204 KB Output is correct
11 Correct 27 ms 24204 KB Output is correct
12 Correct 24 ms 24204 KB Output is correct
13 Correct 25 ms 24204 KB Output is correct
14 Correct 23 ms 24204 KB Output is correct
15 Correct 24 ms 24204 KB Output is correct
16 Correct 23 ms 24204 KB Output is correct
17 Correct 25 ms 24204 KB Output is correct
18 Correct 29 ms 24204 KB Output is correct
19 Correct 23 ms 24204 KB Output is correct
20 Correct 26 ms 24204 KB Output is correct
21 Correct 23 ms 24204 KB Output is correct
22 Correct 24 ms 24204 KB Output is correct
23 Correct 24 ms 24204 KB Output is correct
24 Correct 24 ms 24340 KB Output is correct
25 Correct 24 ms 24340 KB Output is correct
26 Correct 24 ms 24340 KB Output is correct
27 Correct 24 ms 24340 KB Output is correct
28 Correct 24 ms 24340 KB Output is correct
29 Correct 23 ms 24340 KB Output is correct
30 Correct 24 ms 24340 KB Output is correct
31 Correct 24 ms 24340 KB Output is correct
32 Correct 23 ms 24340 KB Output is correct
33 Correct 23 ms 24340 KB Output is correct
34 Correct 23 ms 24340 KB Output is correct
35 Correct 23 ms 24340 KB Output is correct
36 Correct 23 ms 24340 KB Output is correct
37 Correct 24 ms 24340 KB Output is correct
38 Correct 23 ms 24340 KB Output is correct
39 Correct 25 ms 24340 KB Output is correct
40 Correct 23 ms 24340 KB Output is correct
41 Correct 23 ms 24340 KB Output is correct
42 Correct 28 ms 24340 KB Output is correct
43 Correct 23 ms 24340 KB Output is correct
44 Correct 25 ms 24340 KB Output is correct
45 Correct 24 ms 24340 KB Output is correct
46 Correct 24 ms 24340 KB Output is correct
47 Correct 23 ms 24340 KB Output is correct
48 Correct 24 ms 24340 KB Output is correct
49 Correct 23 ms 24340 KB Output is correct
50 Correct 22 ms 24340 KB Output is correct
51 Correct 25 ms 24340 KB Output is correct
52 Correct 22 ms 24340 KB Output is correct
53 Correct 23 ms 24340 KB Output is correct
54 Correct 28 ms 24340 KB Output is correct
55 Correct 22 ms 24340 KB Output is correct
56 Correct 27 ms 24340 KB Output is correct
57 Correct 23 ms 24340 KB Output is correct
58 Correct 26 ms 24340 KB Output is correct
59 Correct 637 ms 49164 KB Output is correct
60 Correct 613 ms 49164 KB Output is correct
61 Correct 24 ms 49164 KB Output is correct
62 Correct 23 ms 49164 KB Output is correct
63 Correct 549 ms 49164 KB Output is correct
64 Correct 27 ms 49164 KB Output is correct
65 Correct 39 ms 49164 KB Output is correct
66 Correct 253 ms 49164 KB Output is correct
67 Correct 977 ms 80828 KB Output is correct
68 Correct 863 ms 80828 KB Output is correct
69 Correct 34 ms 80828 KB Output is correct
70 Correct 165 ms 80828 KB Output is correct
71 Correct 587 ms 80828 KB Output is correct
72 Correct 652 ms 80828 KB Output is correct
73 Correct 171 ms 80828 KB Output is correct
74 Correct 732 ms 80828 KB Output is correct
75 Correct 60 ms 80828 KB Output is correct
76 Correct 532 ms 80828 KB Output is correct
77 Correct 567 ms 80828 KB Output is correct
78 Correct 57 ms 80828 KB Output is correct
79 Correct 796 ms 80828 KB Output is correct
80 Correct 26 ms 80828 KB Output is correct
81 Correct 192 ms 80828 KB Output is correct
82 Correct 643 ms 80828 KB Output is correct
83 Correct 686 ms 80828 KB Output is correct
84 Correct 664 ms 80828 KB Output is correct
85 Correct 620 ms 80828 KB Output is correct
86 Correct 633 ms 80828 KB Output is correct
87 Correct 614 ms 80828 KB Output is correct