oj.uz

답안 #931782

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
931782 2024-02-22T10:51:56 Z vjudge1 Network (BOI15_net) C++17
63 / 100
 316 ms 27080 KB 
#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
using namespace std;

const int N = 2000 + 10, LG = 20;

int n, h[N], par[N][LG];
bool mark[N];
vector<int> G[N], vec;
vector<pair<int, pair<int, int>>> vec1;

void dfs(int v = 1, int p = 0) {
    par[v][0] = p;
    for (auto e : G[v])
        if (e ^ p) {
            h[e] = h[v] + 1;
            dfs(e, v);
        }
}

int lca(int u, int v) {
    if (u == v) return u;
    if (h[u] < h[v]) swap(u, v);
    int k = h[u] - h[v];
    for (int lg = 0; lg < LG; lg++)
        if (k & (1 << lg)) u = par[u][lg];
    if (u == v) return v;
    for (int lg = LG - 1; lg >= 0; lg--)
        if (par[u][lg] != par[v][lg])  u = par[u][lg], v = par[v][lg];
    return par[u][0];
}

int main() {
    ios:: sync_with_stdio(0), cin.tie(0);
    cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        G[u].pb(v);
        G[v].pb(u);
    }
    dfs();
    for (int i = 1; i <= n; i++)
        if (G[i].size() == 1) vec.push_back(i);
    for (int lg = 1; lg < LG; lg++)
        for (int i = 1; i <= n; i++)
            par[i][lg] = par[par[i][lg - 1]][lg - 1];
    for (int i = 0; i < (int)vec.size(); i++) 
        for (int j = i + 1; j < (int)vec.size(); j++) {
            int l = lca(vec[i], vec[j]);
            vec1.pb({h[vec[i]] + h[vec[j]] - 2 * h[l], {vec[i], vec[j]}});
        }
    sort(vec1.begin(), vec1.end());
    reverse(vec1.begin(), vec1.end());
    cout << ((int)vec.size() + 1) / 2 << endl;
    int cnt = 0;
    for (auto e : vec1) {
        if (cnt == (int) vec.size()) return 0;
        if (!mark[e.S.F] && !mark[e.S.S]) {
            cout << e.S.F << ' ' << e.S.S << endl;
            mark[e.S.F] = mark[e.S.S] = true, cnt += 2;
        }
        else if ((int)vec.size() & 1) {
            if (cnt + 1 == (int)vec.size()) {
                if (!mark[e.S.S]) return cout << vec1[0].S.F << ' ' << e.S.S << endl, 0;
                else if (!mark[e.S.F]) return cout << vec1[0].S.F << ' ' << e.S.F << endl, 0;
            }
        }
    }
}

Subtask #1
18.0 / 18.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 1 ms 600 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct

Subtask #2
45.0 / 45.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 1 ms 600 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 282 ms 26428 KB Output is correct
23 Correct 261 ms 25836 KB Output is correct
24 Correct 295 ms 27080 KB Output is correct
25 Correct 92 ms 13468 KB Output is correct
26 Correct 76 ms 7268 KB Output is correct
27 Correct 163 ms 14524 KB Output is correct
28 Correct 147 ms 14520 KB Output is correct
29 Correct 89 ms 8908 KB Output is correct
30 Correct 0 ms 344 KB Output is correct
31 Correct 162 ms 13500 KB Output is correct
32 Correct 1 ms 348 KB Output is correct
33 Correct 1 ms 344 KB Output is correct
34 Correct 0 ms 348 KB Output is correct
35 Correct 1 ms 348 KB Output is correct
36 Correct 1 ms 348 KB Output is correct
37 Correct 1 ms 604 KB Output is correct
38 Correct 1 ms 604 KB Output is correct
39 Correct 0 ms 344 KB Output is correct
40 Correct 1 ms 344 KB Output is correct
41 Correct 1 ms 604 KB Output is correct
42 Correct 13 ms 2264 KB Output is correct
43 Correct 63 ms 7628 KB Output is correct
44 Correct 1 ms 348 KB Output is correct
45 Correct 4 ms 1052 KB Output is correct
46 Correct 23 ms 2264 KB Output is correct
47 Correct 1 ms 344 KB Output is correct
48 Correct 5 ms 1052 KB Output is correct
49 Correct 62 ms 7628 KB Output is correct
50 Correct 1 ms 348 KB Output is correct
51 Correct 1 ms 348 KB Output is correct
52 Correct 1 ms 348 KB Output is correct
53 Correct 12 ms 1368 KB Output is correct
54 Correct 0 ms 348 KB Output is correct
55 Correct 7 ms 1368 KB Output is correct
56 Correct 0 ms 348 KB Output is correct
57 Correct 17 ms 2256 KB Output is correct
58 Correct 316 ms 26832 KB Output is correct

Subtask #3
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 1 ms 600 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 282 ms 26428 KB Output is correct
23 Correct 261 ms 25836 KB Output is correct
24 Correct 295 ms 27080 KB Output is correct
25 Correct 92 ms 13468 KB Output is correct
26 Correct 76 ms 7268 KB Output is correct
27 Correct 163 ms 14524 KB Output is correct
28 Correct 147 ms 14520 KB Output is correct
29 Correct 89 ms 8908 KB Output is correct
30 Correct 0 ms 344 KB Output is correct
31 Correct 162 ms 13500 KB Output is correct
32 Correct 1 ms 348 KB Output is correct
33 Correct 1 ms 344 KB Output is correct
34 Correct 0 ms 348 KB Output is correct
35 Correct 1 ms 348 KB Output is correct
36 Correct 1 ms 348 KB Output is correct
37 Correct 1 ms 604 KB Output is correct
38 Correct 1 ms 604 KB Output is correct
39 Correct 0 ms 344 KB Output is correct
40 Correct 1 ms 344 KB Output is correct
41 Correct 1 ms 604 KB Output is correct
42 Correct 13 ms 2264 KB Output is correct
43 Correct 63 ms 7628 KB Output is correct
44 Correct 1 ms 348 KB Output is correct
45 Correct 4 ms 1052 KB Output is correct
46 Correct 23 ms 2264 KB Output is correct
47 Correct 1 ms 344 KB Output is correct
48 Correct 5 ms 1052 KB Output is correct
49 Correct 62 ms 7628 KB Output is correct
50 Correct 1 ms 348 KB Output is correct
51 Correct 1 ms 348 KB Output is correct
52 Correct 1 ms 348 KB Output is correct
53 Correct 12 ms 1368 KB Output is correct
54 Correct 0 ms 348 KB Output is correct
55 Correct 7 ms 1368 KB Output is correct
56 Correct 0 ms 348 KB Output is correct
57 Correct 17 ms 2256 KB Output is correct
58 Correct 316 ms 26832 KB Output is correct
59 Runtime error 1 ms 604 KB Execution killed with signal 11
60 Halted 0 ms 0 KB -