답안 #1097709

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1097709	2024-10-08T03:30:06 Z	TrinhKhanhDung	Network (BOI15_net)	C++14	100 / 100	264 ms	47952 KB

#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)

using namespace std;

template<class T1, class T2>
    bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}

template<class T1, class T2>
    bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}

template<class T1, class T2>
    void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}

template<class T1, class T2>
    void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}

template<class T>
    void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}

const int MAX = 5e5 + 10;

int N;
vector<int> adj[MAX];
vector<int> leaves;

void dfs(int u, int p = -1){
    if(sz(adj[u]) == 1) leaves.push_back(u);
    for(int v: adj[u]){
        if(v == p) continue;
        dfs(v, u);
    }
}

void solve(){
    cin >> N;
    for(int i = 1; i < N; i++){
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    clock_t start = clock();

    if(N == 2){
        cout << 1 << '\n' << "1 2\n";
        return;
    }

    int root;
    for(int i = 1; i <= N; i++){
        if(sz(adj[i]) > 1){
            root = i;
            break;
        }
    }

    dfs(root);

    vector<pair<int, int>> ans;
    int n = sz(leaves);
    for(int i = 0; i < n / 2; i++){
        ans.push_back({leaves[i], leaves[i + n / 2]});
    }

    if(sz(leaves) & 1){
        ans.push_back({leaves[0], leaves.back()});
    }

    cout << sz(ans) << '\n';
    for(auto o: ans){
        cout << o.fi << ' ' << o.se << '\n';
    }

    cerr << "Time elapsed: " << clock() - start << " ms\n";
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
//    freopen("walk.inp","r",stdin);
//    freopen("walk.out","w",stdout);

    int t = 1;
//    cin >> t;
    while(t--)
        solve();

    return 0;
}

Compilation message

net.cpp: In function 'void solve()':
net.cpp:67:8: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
   67 |     dfs(root);
      |     ~~~^~~~~~

Subtask #1
18.0 / 18.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	12124 KB	Output is correct
2	Correct	5 ms	12124 KB	Output is correct
3	Correct	6 ms	12124 KB	Output is correct
4	Correct	5 ms	12376 KB	Output is correct
5	Correct	6 ms	12124 KB	Output is correct
6	Correct	6 ms	12124 KB	Output is correct
7	Correct	5 ms	12124 KB	Output is correct
8	Correct	6 ms	12124 KB	Output is correct
9	Correct	6 ms	12124 KB	Output is correct
10	Correct	5 ms	12120 KB	Output is correct
11	Correct	5 ms	12124 KB	Output is correct
12	Correct	6 ms	12124 KB	Output is correct
13	Correct	6 ms	12124 KB	Output is correct
14	Correct	5 ms	12120 KB	Output is correct
15	Correct	6 ms	12124 KB	Output is correct
16	Correct	5 ms	12124 KB	Output is correct
17	Correct	5 ms	12196 KB	Output is correct
18	Correct	5 ms	12120 KB	Output is correct
19	Correct	5 ms	12124 KB	Output is correct
20	Correct	5 ms	12124 KB	Output is correct

Subtask #2
45.0 / 45.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	12124 KB	Output is correct
2	Correct	5 ms	12124 KB	Output is correct
3	Correct	6 ms	12124 KB	Output is correct
4	Correct	5 ms	12376 KB	Output is correct
5	Correct	6 ms	12124 KB	Output is correct
6	Correct	6 ms	12124 KB	Output is correct
7	Correct	5 ms	12124 KB	Output is correct
8	Correct	6 ms	12124 KB	Output is correct
9	Correct	6 ms	12124 KB	Output is correct
10	Correct	5 ms	12120 KB	Output is correct
11	Correct	5 ms	12124 KB	Output is correct
12	Correct	6 ms	12124 KB	Output is correct
13	Correct	6 ms	12124 KB	Output is correct
14	Correct	5 ms	12120 KB	Output is correct
15	Correct	6 ms	12124 KB	Output is correct
16	Correct	5 ms	12124 KB	Output is correct
17	Correct	5 ms	12196 KB	Output is correct
18	Correct	5 ms	12120 KB	Output is correct
19	Correct	5 ms	12124 KB	Output is correct
20	Correct	5 ms	12124 KB	Output is correct
21	Correct	6 ms	12120 KB	Output is correct
22	Correct	5 ms	12124 KB	Output is correct
23	Correct	5 ms	12124 KB	Output is correct
24	Correct	5 ms	12124 KB	Output is correct
25	Correct	6 ms	12124 KB	Output is correct
26	Correct	6 ms	12124 KB	Output is correct
27	Correct	6 ms	12124 KB	Output is correct
28	Correct	7 ms	12120 KB	Output is correct
29	Correct	6 ms	12124 KB	Output is correct
30	Correct	6 ms	12124 KB	Output is correct
31	Correct	5 ms	12124 KB	Output is correct
32	Correct	6 ms	12124 KB	Output is correct
33	Correct	5 ms	12124 KB	Output is correct
34	Correct	7 ms	12196 KB	Output is correct
35	Correct	6 ms	12376 KB	Output is correct
36	Correct	5 ms	12124 KB	Output is correct
37	Correct	5 ms	12124 KB	Output is correct
38	Correct	7 ms	12216 KB	Output is correct
39	Correct	5 ms	12124 KB	Output is correct
40	Correct	4 ms	12204 KB	Output is correct
41	Correct	5 ms	12124 KB	Output is correct
42	Correct	5 ms	12124 KB	Output is correct
43	Correct	5 ms	12124 KB	Output is correct
44	Correct	5 ms	12196 KB	Output is correct
45	Correct	6 ms	12376 KB	Output is correct
46	Correct	5 ms	12120 KB	Output is correct
47	Correct	5 ms	12124 KB	Output is correct
48	Correct	5 ms	12124 KB	Output is correct
49	Correct	6 ms	12140 KB	Output is correct
50	Correct	5 ms	12124 KB	Output is correct
51	Correct	6 ms	12124 KB	Output is correct
52	Correct	5 ms	12124 KB	Output is correct
53	Correct	5 ms	12124 KB	Output is correct
54	Correct	5 ms	12120 KB	Output is correct
55	Correct	5 ms	12124 KB	Output is correct
56	Correct	5 ms	12124 KB	Output is correct
57	Correct	5 ms	12120 KB	Output is correct
58	Correct	5 ms	12124 KB	Output is correct

Subtask #3
37.0 / 37.0

#	결과	실행 시간	메모리	Grader output
1	Correct	6 ms	12124 KB	Output is correct
2	Correct	5 ms	12124 KB	Output is correct
3	Correct	6 ms	12124 KB	Output is correct
4	Correct	5 ms	12376 KB	Output is correct
5	Correct	6 ms	12124 KB	Output is correct
6	Correct	6 ms	12124 KB	Output is correct
7	Correct	5 ms	12124 KB	Output is correct
8	Correct	6 ms	12124 KB	Output is correct
9	Correct	6 ms	12124 KB	Output is correct
10	Correct	5 ms	12120 KB	Output is correct
11	Correct	5 ms	12124 KB	Output is correct
12	Correct	6 ms	12124 KB	Output is correct
13	Correct	6 ms	12124 KB	Output is correct
14	Correct	5 ms	12120 KB	Output is correct
15	Correct	6 ms	12124 KB	Output is correct
16	Correct	5 ms	12124 KB	Output is correct
17	Correct	5 ms	12196 KB	Output is correct
18	Correct	5 ms	12120 KB	Output is correct
19	Correct	5 ms	12124 KB	Output is correct
20	Correct	5 ms	12124 KB	Output is correct
21	Correct	6 ms	12120 KB	Output is correct
22	Correct	5 ms	12124 KB	Output is correct
23	Correct	5 ms	12124 KB	Output is correct
24	Correct	5 ms	12124 KB	Output is correct
25	Correct	6 ms	12124 KB	Output is correct
26	Correct	6 ms	12124 KB	Output is correct
27	Correct	6 ms	12124 KB	Output is correct
28	Correct	7 ms	12120 KB	Output is correct
29	Correct	6 ms	12124 KB	Output is correct
30	Correct	6 ms	12124 KB	Output is correct
31	Correct	5 ms	12124 KB	Output is correct
32	Correct	6 ms	12124 KB	Output is correct
33	Correct	5 ms	12124 KB	Output is correct
34	Correct	7 ms	12196 KB	Output is correct
35	Correct	6 ms	12376 KB	Output is correct
36	Correct	5 ms	12124 KB	Output is correct
37	Correct	5 ms	12124 KB	Output is correct
38	Correct	7 ms	12216 KB	Output is correct
39	Correct	5 ms	12124 KB	Output is correct
40	Correct	4 ms	12204 KB	Output is correct
41	Correct	5 ms	12124 KB	Output is correct
42	Correct	5 ms	12124 KB	Output is correct
43	Correct	5 ms	12124 KB	Output is correct
44	Correct	5 ms	12196 KB	Output is correct
45	Correct	6 ms	12376 KB	Output is correct
46	Correct	5 ms	12120 KB	Output is correct
47	Correct	5 ms	12124 KB	Output is correct
48	Correct	5 ms	12124 KB	Output is correct
49	Correct	6 ms	12140 KB	Output is correct
50	Correct	5 ms	12124 KB	Output is correct
51	Correct	6 ms	12124 KB	Output is correct
52	Correct	5 ms	12124 KB	Output is correct
53	Correct	5 ms	12124 KB	Output is correct
54	Correct	5 ms	12120 KB	Output is correct
55	Correct	5 ms	12124 KB	Output is correct
56	Correct	5 ms	12124 KB	Output is correct
57	Correct	5 ms	12120 KB	Output is correct
58	Correct	5 ms	12124 KB	Output is correct
59	Correct	166 ms	37312 KB	Output is correct
60	Correct	192 ms	40096 KB	Output is correct
61	Correct	5 ms	12124 KB	Output is correct
62	Correct	5 ms	12124 KB	Output is correct
63	Correct	133 ms	34692 KB	Output is correct
64	Correct	6 ms	12636 KB	Output is correct
65	Correct	12 ms	13912 KB	Output is correct
66	Correct	65 ms	27984 KB	Output is correct
67	Correct	264 ms	47096 KB	Output is correct
68	Correct	249 ms	47952 KB	Output is correct
69	Correct	9 ms	13148 KB	Output is correct
70	Correct	48 ms	21960 KB	Output is correct
71	Correct	179 ms	43976 KB	Output is correct
72	Correct	169 ms	42520 KB	Output is correct
73	Correct	54 ms	19412 KB	Output is correct
74	Correct	213 ms	38656 KB	Output is correct
75	Correct	18 ms	15448 KB	Output is correct
76	Correct	184 ms	43464 KB	Output is correct
77	Correct	161 ms	43556 KB	Output is correct
78	Correct	21 ms	15708 KB	Output is correct
79	Correct	250 ms	45136 KB	Output is correct
80	Correct	6 ms	12376 KB	Output is correct
81	Correct	54 ms	21872 KB	Output is correct
82	Correct	186 ms	41136 KB	Output is correct
83	Correct	199 ms	38736 KB	Output is correct
84	Correct	228 ms	38704 KB	Output is correct
85	Correct	223 ms	38616 KB	Output is correct
86	Correct	238 ms	40012 KB	Output is correct
87	Correct	190 ms	40000 KB	Output is correct

답안 #1097709

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