답안 #390058

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
390058	2021-04-15T07:46:51 Z	BThero	Network (BOI15_net)	C++17	100 / 100	688 ms	58172 KB

// chrono::system_clock::now().time_since_epoch().count()
#include <bits/stdc++.h>

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define debug(x) cerr << #x << " = " << x << endl

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int MAXN = (int)5e5 + 5;

vi adj[MAXN], leaf;
int sub[MAXN];
int n, m;

void dfs(int v, int pr = -1) {
    sub[v] = (sz(adj[v]) == 1);

    for (int to : adj[v]) {
        if (pr != to) {
            dfs(to, v);
            sub[v] += sub[to];
        }
    }
}

int cen(int v, int lim, int pr = -1) {
    for (int to : adj[v]) {
        if (to != pr && sub[to] > lim / 2) {
            return cen(to, lim, v);
        }
    }

    return v;
}

void dfsCol(int v, int pr, int c) {
    if (sz(adj[v]) == 1) {
        leaf.pb(v);
    }

    for (int to : adj[v]) {
        if (to != pr) {
            dfsCol(to, v, c);
        }
    }
}

void solve() {
    cin >> n;

    rep (i, 1, n) {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    dfs(1);
    int tot = sub[1];
    int root = cen(1, tot);

    for (int to : adj[root]) {
        dfsCol(to, root, ++m);
    }
    
    cout << (tot + 1) / 2 << '\n';

    if (tot % 2 == 0) {
        for (int i = 0; i < tot / 2; i++) {
            cout << leaf[i] << ' ' << leaf[i + tot / 2] << '\n';
        }
    }
    else {
        for (int i = 0; i <= tot / 2; i++) {
            cout << leaf[i] << ' ' << leaf[i + tot / 2] << '\n';
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int tt = 1;

    for (int i = 1; i <= tt; ++i) {
        solve();
    }

    return 0;
}

Subtask #1
18.0 / 18.0

#	결과	실행 시간	메모리	Grader output
1	Correct	7 ms	11980 KB	Output is correct
2	Correct	7 ms	11980 KB	Output is correct
3	Correct	8 ms	11980 KB	Output is correct
4	Correct	7 ms	11980 KB	Output is correct
5	Correct	7 ms	11980 KB	Output is correct
6	Correct	8 ms	11980 KB	Output is correct
7	Correct	7 ms	11980 KB	Output is correct
8	Correct	7 ms	11980 KB	Output is correct
9	Correct	7 ms	12072 KB	Output is correct
10	Correct	7 ms	12012 KB	Output is correct
11	Correct	8 ms	11980 KB	Output is correct
12	Correct	7 ms	12068 KB	Output is correct
13	Correct	7 ms	11980 KB	Output is correct
14	Correct	7 ms	11980 KB	Output is correct
15	Correct	8 ms	12056 KB	Output is correct
16	Correct	8 ms	12036 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	8 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	8 ms	11980 KB	Output is correct

Subtask #2
45.0 / 45.0

#	결과	실행 시간	메모리	Grader output
1	Correct	7 ms	11980 KB	Output is correct
2	Correct	7 ms	11980 KB	Output is correct
3	Correct	8 ms	11980 KB	Output is correct
4	Correct	7 ms	11980 KB	Output is correct
5	Correct	7 ms	11980 KB	Output is correct
6	Correct	8 ms	11980 KB	Output is correct
7	Correct	7 ms	11980 KB	Output is correct
8	Correct	7 ms	11980 KB	Output is correct
9	Correct	7 ms	12072 KB	Output is correct
10	Correct	7 ms	12012 KB	Output is correct
11	Correct	8 ms	11980 KB	Output is correct
12	Correct	7 ms	12068 KB	Output is correct
13	Correct	7 ms	11980 KB	Output is correct
14	Correct	7 ms	11980 KB	Output is correct
15	Correct	8 ms	12056 KB	Output is correct
16	Correct	8 ms	12036 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	8 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	8 ms	11980 KB	Output is correct
21	Correct	7 ms	11980 KB	Output is correct
22	Correct	8 ms	12172 KB	Output is correct
23	Correct	8 ms	12160 KB	Output is correct
24	Correct	9 ms	12156 KB	Output is correct
25	Correct	8 ms	12108 KB	Output is correct
26	Correct	8 ms	12064 KB	Output is correct
27	Correct	8 ms	12080 KB	Output is correct
28	Correct	8 ms	12108 KB	Output is correct
29	Correct	8 ms	12036 KB	Output is correct
30	Correct	7 ms	11980 KB	Output is correct
31	Correct	8 ms	12108 KB	Output is correct
32	Correct	7 ms	11980 KB	Output is correct
33	Correct	7 ms	11980 KB	Output is correct
34	Correct	7 ms	11980 KB	Output is correct
35	Correct	7 ms	11980 KB	Output is correct
36	Correct	8 ms	11980 KB	Output is correct
37	Correct	8 ms	12076 KB	Output is correct
38	Correct	8 ms	12140 KB	Output is correct
39	Correct	8 ms	11980 KB	Output is correct
40	Correct	9 ms	11980 KB	Output is correct
41	Correct	8 ms	11980 KB	Output is correct
42	Correct	7 ms	11980 KB	Output is correct
43	Correct	8 ms	12052 KB	Output is correct
44	Correct	8 ms	12064 KB	Output is correct
45	Correct	8 ms	12060 KB	Output is correct
46	Correct	8 ms	12236 KB	Output is correct
47	Correct	9 ms	11980 KB	Output is correct
48	Correct	8 ms	11980 KB	Output is correct
49	Correct	8 ms	12108 KB	Output is correct
50	Correct	7 ms	12068 KB	Output is correct
51	Correct	7 ms	12056 KB	Output is correct
52	Correct	8 ms	11980 KB	Output is correct
53	Correct	8 ms	12108 KB	Output is correct
54	Correct	7 ms	11980 KB	Output is correct
55	Correct	7 ms	11992 KB	Output is correct
56	Correct	7 ms	11980 KB	Output is correct
57	Correct	8 ms	11980 KB	Output is correct
58	Correct	8 ms	12080 KB	Output is correct

Subtask #3
37.0 / 37.0

#	결과	실행 시간	메모리	Grader output
1	Correct	7 ms	11980 KB	Output is correct
2	Correct	7 ms	11980 KB	Output is correct
3	Correct	8 ms	11980 KB	Output is correct
4	Correct	7 ms	11980 KB	Output is correct
5	Correct	7 ms	11980 KB	Output is correct
6	Correct	8 ms	11980 KB	Output is correct
7	Correct	7 ms	11980 KB	Output is correct
8	Correct	7 ms	11980 KB	Output is correct
9	Correct	7 ms	12072 KB	Output is correct
10	Correct	7 ms	12012 KB	Output is correct
11	Correct	8 ms	11980 KB	Output is correct
12	Correct	7 ms	12068 KB	Output is correct
13	Correct	7 ms	11980 KB	Output is correct
14	Correct	7 ms	11980 KB	Output is correct
15	Correct	8 ms	12056 KB	Output is correct
16	Correct	8 ms	12036 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	8 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	8 ms	11980 KB	Output is correct
21	Correct	7 ms	11980 KB	Output is correct
22	Correct	8 ms	12172 KB	Output is correct
23	Correct	8 ms	12160 KB	Output is correct
24	Correct	9 ms	12156 KB	Output is correct
25	Correct	8 ms	12108 KB	Output is correct
26	Correct	8 ms	12064 KB	Output is correct
27	Correct	8 ms	12080 KB	Output is correct
28	Correct	8 ms	12108 KB	Output is correct
29	Correct	8 ms	12036 KB	Output is correct
30	Correct	7 ms	11980 KB	Output is correct
31	Correct	8 ms	12108 KB	Output is correct
32	Correct	7 ms	11980 KB	Output is correct
33	Correct	7 ms	11980 KB	Output is correct
34	Correct	7 ms	11980 KB	Output is correct
35	Correct	7 ms	11980 KB	Output is correct
36	Correct	8 ms	11980 KB	Output is correct
37	Correct	8 ms	12076 KB	Output is correct
38	Correct	8 ms	12140 KB	Output is correct
39	Correct	8 ms	11980 KB	Output is correct
40	Correct	9 ms	11980 KB	Output is correct
41	Correct	8 ms	11980 KB	Output is correct
42	Correct	7 ms	11980 KB	Output is correct
43	Correct	8 ms	12052 KB	Output is correct
44	Correct	8 ms	12064 KB	Output is correct
45	Correct	8 ms	12060 KB	Output is correct
46	Correct	8 ms	12236 KB	Output is correct
47	Correct	9 ms	11980 KB	Output is correct
48	Correct	8 ms	11980 KB	Output is correct
49	Correct	8 ms	12108 KB	Output is correct
50	Correct	7 ms	12068 KB	Output is correct
51	Correct	7 ms	12056 KB	Output is correct
52	Correct	8 ms	11980 KB	Output is correct
53	Correct	8 ms	12108 KB	Output is correct
54	Correct	7 ms	11980 KB	Output is correct
55	Correct	7 ms	11992 KB	Output is correct
56	Correct	7 ms	11980 KB	Output is correct
57	Correct	8 ms	11980 KB	Output is correct
58	Correct	8 ms	12080 KB	Output is correct
59	Correct	465 ms	37852 KB	Output is correct
60	Correct	557 ms	40628 KB	Output is correct
61	Correct	7 ms	11980 KB	Output is correct
62	Correct	7 ms	11980 KB	Output is correct
63	Correct	397 ms	35184 KB	Output is correct
64	Correct	10 ms	12620 KB	Output is correct
65	Correct	20 ms	14612 KB	Output is correct
66	Correct	208 ms	33868 KB	Output is correct
67	Correct	665 ms	57272 KB	Output is correct
68	Correct	672 ms	58172 KB	Output is correct
69	Correct	14 ms	13004 KB	Output is correct
70	Correct	113 ms	21904 KB	Output is correct
71	Correct	362 ms	43820 KB	Output is correct
72	Correct	391 ms	42620 KB	Output is correct
73	Correct	137 ms	19628 KB	Output is correct
74	Correct	571 ms	39624 KB	Output is correct
75	Correct	36 ms	15428 KB	Output is correct
76	Correct	386 ms	43480 KB	Output is correct
77	Correct	378 ms	43596 KB	Output is correct
78	Correct	39 ms	16052 KB	Output is correct
79	Correct	688 ms	54332 KB	Output is correct
80	Correct	9 ms	12236 KB	Output is correct
81	Correct	129 ms	21908 KB	Output is correct
82	Correct	482 ms	41400 KB	Output is correct
83	Correct	578 ms	39640 KB	Output is correct
84	Correct	578 ms	39760 KB	Output is correct
85	Correct	583 ms	39564 KB	Output is correct
86	Correct	563 ms	40788 KB	Output is correct
87	Correct	562 ms	40628 KB	Output is correct

답안 #390058

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0