답안 #527509

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
527509	2022-02-17T14:03:09 Z	jalsol	Network (BOI15_net)	C++11	100 / 100	421 ms	47520 KB

#include <bits/stdc++.h>

using namespace std;

#define Task ""

struct __Init__ {
    __Init__() {
        cin.tie(nullptr)->sync_with_stdio(false);
        if (fopen(Task".inp", "r")) {
            freopen(Task".inp", "r", stdin);
            freopen(Task".out", "w", stdout); }
    }
} __init__;

using ll = long long;

#ifdef LOCAL
#define debug(x) cerr << "[" #x " = " << x << "]\n";
#else
#define debug(...)
#endif // LOCAL

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define fi first
#define se second

#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)

template<class C> int isz(const C& c) { return c.size(); }
template<class T> bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }

constexpr int eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;

// =============================================================================

constexpr int maxN = 5e5 + 5;

int n;
vector<int> g[maxN];

vector<int> child;

void Dfs(int u, int p) {
    bool hasChild = false;

    for (int v : g[u]) {
        if (v != p) {
            hasChild = true;
            Dfs(v, u);
        }
    }

    if (!hasChild) {
        child.push_back(u);
    }
}

signed main() {
    cin >> n;

    For (i, 1, n - 1) {
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    int root = -1;
    For (i, 1, n) {
        if (isz(g[i]) > 1) {
            root = i;
            break;
        }
    }

    child.reserve(n);
    Dfs(root, -1);

    int ans = (isz(child) + 1) / 2;
    cout << ans << '\n';

    Rep (i, ans) {
        cout << child[i] << ' ' << child[i + isz(child) / 2] << '\n';
    }
}

/*

*/

Compilation message

net.cpp: In constructor '__Init__::__Init__()':
net.cpp:11:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |             freopen(Task".inp", "r", stdin);
      |             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:12:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |             freopen(Task".out", "w", stdout); }
      |             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	11980 KB	Output is correct
2	Correct	6 ms	12016 KB	Output is correct
3	Correct	6 ms	12052 KB	Output is correct
4	Correct	7 ms	12036 KB	Output is correct
5	Correct	7 ms	12052 KB	Output is correct
6	Correct	6 ms	12052 KB	Output is correct
7	Correct	6 ms	11980 KB	Output is correct
8	Correct	7 ms	12040 KB	Output is correct
9	Correct	6 ms	11980 KB	Output is correct
10	Correct	7 ms	12060 KB	Output is correct
11	Correct	7 ms	12044 KB	Output is correct
12	Correct	6 ms	11980 KB	Output is correct
13	Correct	6 ms	12056 KB	Output is correct
14	Correct	6 ms	11980 KB	Output is correct
15	Correct	6 ms	11980 KB	Output is correct
16	Correct	7 ms	11980 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	7 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	7 ms	11968 KB	Output is correct

Subtask #2
45.0 / 45.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	11980 KB	Output is correct
2	Correct	6 ms	12016 KB	Output is correct
3	Correct	6 ms	12052 KB	Output is correct
4	Correct	7 ms	12036 KB	Output is correct
5	Correct	7 ms	12052 KB	Output is correct
6	Correct	6 ms	12052 KB	Output is correct
7	Correct	6 ms	11980 KB	Output is correct
8	Correct	7 ms	12040 KB	Output is correct
9	Correct	6 ms	11980 KB	Output is correct
10	Correct	7 ms	12060 KB	Output is correct
11	Correct	7 ms	12044 KB	Output is correct
12	Correct	6 ms	11980 KB	Output is correct
13	Correct	6 ms	12056 KB	Output is correct
14	Correct	6 ms	11980 KB	Output is correct
15	Correct	6 ms	11980 KB	Output is correct
16	Correct	7 ms	11980 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	7 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	7 ms	11968 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	7 ms	12108 KB	Output is correct
25	Correct	7 ms	12108 KB	Output is correct
26	Correct	7 ms	12108 KB	Output is correct
27	Correct	8 ms	12044 KB	Output is correct
28	Correct	7 ms	12108 KB	Output is correct
29	Correct	7 ms	12108 KB	Output is correct
30	Correct	6 ms	11980 KB	Output is correct
31	Correct	8 ms	12108 KB	Output is correct
32	Correct	6 ms	12056 KB	Output is correct
33	Correct	7 ms	11996 KB	Output is correct
34	Correct	6 ms	11980 KB	Output is correct
35	Correct	7 ms	11980 KB	Output is correct
36	Correct	7 ms	11984 KB	Output is correct
37	Correct	7 ms	12108 KB	Output is correct
38	Correct	9 ms	12108 KB	Output is correct
39	Correct	6 ms	11948 KB	Output is correct
40	Correct	7 ms	12052 KB	Output is correct
41	Correct	6 ms	12064 KB	Output is correct
42	Correct	7 ms	12060 KB	Output is correct
43	Correct	7 ms	12108 KB	Output is correct
44	Correct	7 ms	11980 KB	Output is correct
45	Correct	6 ms	12060 KB	Output is correct
46	Correct	6 ms	12056 KB	Output is correct
47	Correct	7 ms	12056 KB	Output is correct
48	Correct	7 ms	12108 KB	Output is correct
49	Correct	7 ms	12064 KB	Output is correct
50	Correct	8 ms	11980 KB	Output is correct
51	Correct	6 ms	11980 KB	Output is correct
52	Correct	7 ms	12056 KB	Output is correct
53	Correct	7 ms	11980 KB	Output is correct
54	Correct	7 ms	12052 KB	Output is correct
55	Correct	7 ms	12060 KB	Output is correct
56	Correct	7 ms	12056 KB	Output is correct
57	Correct	7 ms	12060 KB	Output is correct
58	Correct	7 ms	12060 KB	Output is correct

Subtask #3
37.0 / 37.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	11980 KB	Output is correct
2	Correct	6 ms	12016 KB	Output is correct
3	Correct	6 ms	12052 KB	Output is correct
4	Correct	7 ms	12036 KB	Output is correct
5	Correct	7 ms	12052 KB	Output is correct
6	Correct	6 ms	12052 KB	Output is correct
7	Correct	6 ms	11980 KB	Output is correct
8	Correct	7 ms	12040 KB	Output is correct
9	Correct	6 ms	11980 KB	Output is correct
10	Correct	7 ms	12060 KB	Output is correct
11	Correct	7 ms	12044 KB	Output is correct
12	Correct	6 ms	11980 KB	Output is correct
13	Correct	6 ms	12056 KB	Output is correct
14	Correct	6 ms	11980 KB	Output is correct
15	Correct	6 ms	11980 KB	Output is correct
16	Correct	7 ms	11980 KB	Output is correct
17	Correct	7 ms	11980 KB	Output is correct
18	Correct	7 ms	11980 KB	Output is correct
19	Correct	7 ms	11980 KB	Output is correct
20	Correct	7 ms	11968 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	7 ms	12108 KB	Output is correct
25	Correct	7 ms	12108 KB	Output is correct
26	Correct	7 ms	12108 KB	Output is correct
27	Correct	8 ms	12044 KB	Output is correct
28	Correct	7 ms	12108 KB	Output is correct
29	Correct	7 ms	12108 KB	Output is correct
30	Correct	6 ms	11980 KB	Output is correct
31	Correct	8 ms	12108 KB	Output is correct
32	Correct	6 ms	12056 KB	Output is correct
33	Correct	7 ms	11996 KB	Output is correct
34	Correct	6 ms	11980 KB	Output is correct
35	Correct	7 ms	11980 KB	Output is correct
36	Correct	7 ms	11984 KB	Output is correct
37	Correct	7 ms	12108 KB	Output is correct
38	Correct	9 ms	12108 KB	Output is correct
39	Correct	6 ms	11948 KB	Output is correct
40	Correct	7 ms	12052 KB	Output is correct
41	Correct	6 ms	12064 KB	Output is correct
42	Correct	7 ms	12060 KB	Output is correct
43	Correct	7 ms	12108 KB	Output is correct
44	Correct	7 ms	11980 KB	Output is correct
45	Correct	6 ms	12060 KB	Output is correct
46	Correct	6 ms	12056 KB	Output is correct
47	Correct	7 ms	12056 KB	Output is correct
48	Correct	7 ms	12108 KB	Output is correct
49	Correct	7 ms	12064 KB	Output is correct
50	Correct	8 ms	11980 KB	Output is correct
51	Correct	6 ms	11980 KB	Output is correct
52	Correct	7 ms	12056 KB	Output is correct
53	Correct	7 ms	11980 KB	Output is correct
54	Correct	7 ms	12052 KB	Output is correct
55	Correct	7 ms	12060 KB	Output is correct
56	Correct	7 ms	12056 KB	Output is correct
57	Correct	7 ms	12060 KB	Output is correct
58	Correct	7 ms	12060 KB	Output is correct
59	Correct	293 ms	30520 KB	Output is correct
60	Correct	350 ms	38660 KB	Output is correct
61	Correct	6 ms	11980 KB	Output is correct
62	Correct	6 ms	11980 KB	Output is correct
63	Correct	249 ms	33432 KB	Output is correct
64	Correct	8 ms	12484 KB	Output is correct
65	Correct	14 ms	13828 KB	Output is correct
66	Correct	106 ms	27812 KB	Output is correct
67	Correct	386 ms	46908 KB	Output is correct
68	Correct	402 ms	47520 KB	Output is correct
69	Correct	11 ms	12740 KB	Output is correct
70	Correct	66 ms	21152 KB	Output is correct
71	Correct	255 ms	41740 KB	Output is correct
72	Correct	251 ms	40532 KB	Output is correct
73	Correct	68 ms	18848 KB	Output is correct
74	Correct	394 ms	37572 KB	Output is correct
75	Correct	26 ms	15084 KB	Output is correct
76	Correct	273 ms	41412 KB	Output is correct
77	Correct	266 ms	41440 KB	Output is correct
78	Correct	28 ms	15392 KB	Output is correct
79	Correct	421 ms	45176 KB	Output is correct
80	Correct	8 ms	12180 KB	Output is correct
81	Correct	104 ms	21120 KB	Output is correct
82	Correct	352 ms	39388 KB	Output is correct
83	Correct	381 ms	37568 KB	Output is correct
84	Correct	377 ms	37620 KB	Output is correct
85	Correct	405 ms	37496 KB	Output is correct
86	Correct	367 ms	38600 KB	Output is correct
87	Correct	341 ms	38684 KB	Output is correct

답안 #527509

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