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답안 #782514

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
782514 2023-07-14T03:51:24 Z skittles1412 Network (BOI15_net) C++17
100 / 100
 592 ms 101204 KB 
#include "bits/extc++.h"

using namespace std;

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t;
    ((cerr << " | " << u), ...);
    cerr << endl;
}

#ifdef DEBUG
#define dbg(...)                                           \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
         << ": ";                                          \
    dbgh(__VA_ARGS__)
#else
#define cerr   \
    if (false) \
    cerr
#define dbg(...)
#endif

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

constexpr int maxn = 5e5 + 5;

int r1[maxn];
vector<pair<int, int>> ans;
vector<int> graph[maxn];

void pdfs(int u, int p, int r) {
    if (r == -1 && p != -1) {
        r = u;
    }
    r1[u] = r;

    for (auto& v : graph[u]) {
        if (v == p) {
            continue;
        }
        pdfs(v, u, r);
    }
}

vector<int> dfs(int u, int p) {
    if (sz(graph[u]) == 1) {
        return {u};
    }

    vector<int> unmatched;
    for (auto& v : graph[u]) {
        if (v == p) {
            continue;
        }

        auto ch = dfs(v, u);

        while (sz(unmatched) > 1 && sz(ch)) {
            ans.emplace_back(unmatched.back(), ch.back());
            unmatched.pop_back();
            ch.pop_back();
        }

        unmatched.insert(unmatched.end(), begin(ch), end(ch));
        assert(sz(unmatched) <= 3);
    }

    if (sz(unmatched) == 3) {
        ans.emplace_back(unmatched[0], unmatched[1]);
        unmatched = {unmatched[2]};
    }

    if (p == -1 && sz(unmatched)) {
        if (sz(unmatched) == 2) {
            ans.emplace_back(unmatched[0], unmatched[1]);
        } else {
            assert(sz(unmatched) == 1);
            int left = unmatched[0];
            for (auto& v : graph[u]) {
                assert(v == r1[v]);
                if (v != r1[left]) {
                    ans.emplace_back(v, left);
                    unmatched.pop_back();
                    break;
                }
            }
            assert(!sz(unmatched));
        }
    }

    return unmatched;
}

void solve() {
    int n;
    cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        u--;
        v--;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    for (int i = 0; i < n; i++) {
        if (sz(graph[i]) < 2) {
            continue;
        }
        pdfs(i, -1, -1);
        dfs(i, -1);
        break;
    }

    cout << sz(ans) << endl;
    for (auto& [u, v] : ans) {
        cout << u + 1 << " " << v + 1 << endl;
    }
}

int main() {
    cin.tie(nullptr);
    cin.exceptions(ios::failbit);
    ios_base::sync_with_stdio(false);
    solve();
}

Subtask #1
18.0 / 18.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 12076 KB Output is correct
2 Correct 7 ms 12076 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 6 ms 12012 KB Output is correct
5 Correct 5 ms 12068 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 12072 KB Output is correct
8 Correct 6 ms 11964 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 5 ms 11988 KB Output is correct
11 Correct 7 ms 12068 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11976 KB Output is correct
14 Correct 6 ms 12068 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 12076 KB Output is correct
18 Correct 5 ms 12036 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 5 ms 11988 KB Output is correct

Subtask #2
45.0 / 45.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 12076 KB Output is correct
2 Correct 7 ms 12076 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 6 ms 12012 KB Output is correct
5 Correct 5 ms 12068 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 12072 KB Output is correct
8 Correct 6 ms 11964 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 5 ms 11988 KB Output is correct
11 Correct 7 ms 12068 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11976 KB Output is correct
14 Correct 6 ms 12068 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 12076 KB Output is correct
18 Correct 5 ms 12036 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 5 ms 11988 KB Output is correct
21 Correct 6 ms 12076 KB Output is correct
22 Correct 6 ms 12116 KB Output is correct
23 Correct 8 ms 12244 KB Output is correct
24 Correct 6 ms 12120 KB Output is correct
25 Correct 6 ms 12116 KB Output is correct
26 Correct 7 ms 12116 KB Output is correct
27 Correct 6 ms 12084 KB Output is correct
28 Correct 6 ms 12116 KB Output is correct
29 Correct 6 ms 12056 KB Output is correct
30 Correct 5 ms 12016 KB Output is correct
31 Correct 6 ms 12080 KB Output is correct
32 Correct 6 ms 12072 KB Output is correct
33 Correct 6 ms 11988 KB Output is correct
34 Correct 6 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 7 ms 12076 KB Output is correct
37 Correct 5 ms 12116 KB Output is correct
38 Correct 7 ms 12208 KB Output is correct
39 Correct 7 ms 12072 KB Output is correct
40 Correct 5 ms 11988 KB Output is correct
41 Correct 6 ms 12068 KB Output is correct
42 Correct 6 ms 11988 KB Output is correct
43 Correct 6 ms 12076 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 7 ms 11988 KB Output is correct
46 Correct 6 ms 12072 KB Output is correct
47 Correct 7 ms 12072 KB Output is correct
48 Correct 6 ms 11988 KB Output is correct
49 Correct 6 ms 12108 KB Output is correct
50 Correct 6 ms 12028 KB Output is correct
51 Correct 6 ms 12068 KB Output is correct
52 Correct 6 ms 12116 KB Output is correct
53 Correct 6 ms 12116 KB Output is correct
54 Correct 7 ms 12032 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 11988 KB Output is correct
57 Correct 7 ms 12068 KB Output is correct
58 Correct 6 ms 12116 KB Output is correct

Subtask #3
37.0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 12076 KB Output is correct
2 Correct 7 ms 12076 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 6 ms 12012 KB Output is correct
5 Correct 5 ms 12068 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 12072 KB Output is correct
8 Correct 6 ms 11964 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 5 ms 11988 KB Output is correct
11 Correct 7 ms 12068 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11976 KB Output is correct
14 Correct 6 ms 12068 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 12076 KB Output is correct
18 Correct 5 ms 12036 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 5 ms 11988 KB Output is correct
21 Correct 6 ms 12076 KB Output is correct
22 Correct 6 ms 12116 KB Output is correct
23 Correct 8 ms 12244 KB Output is correct
24 Correct 6 ms 12120 KB Output is correct
25 Correct 6 ms 12116 KB Output is correct
26 Correct 7 ms 12116 KB Output is correct
27 Correct 6 ms 12084 KB Output is correct
28 Correct 6 ms 12116 KB Output is correct
29 Correct 6 ms 12056 KB Output is correct
30 Correct 5 ms 12016 KB Output is correct
31 Correct 6 ms 12080 KB Output is correct
32 Correct 6 ms 12072 KB Output is correct
33 Correct 6 ms 11988 KB Output is correct
34 Correct 6 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 7 ms 12076 KB Output is correct
37 Correct 5 ms 12116 KB Output is correct
38 Correct 7 ms 12208 KB Output is correct
39 Correct 7 ms 12072 KB Output is correct
40 Correct 5 ms 11988 KB Output is correct
41 Correct 6 ms 12068 KB Output is correct
42 Correct 6 ms 11988 KB Output is correct
43 Correct 6 ms 12076 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 7 ms 11988 KB Output is correct
46 Correct 6 ms 12072 KB Output is correct
47 Correct 7 ms 12072 KB Output is correct
48 Correct 6 ms 11988 KB Output is correct
49 Correct 6 ms 12108 KB Output is correct
50 Correct 6 ms 12028 KB Output is correct
51 Correct 6 ms 12068 KB Output is correct
52 Correct 6 ms 12116 KB Output is correct
53 Correct 6 ms 12116 KB Output is correct
54 Correct 7 ms 12032 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 11988 KB Output is correct
57 Correct 7 ms 12068 KB Output is correct
58 Correct 6 ms 12116 KB Output is correct
59 Correct 303 ms 37796 KB Output is correct
60 Correct 334 ms 40696 KB Output is correct
61 Correct 6 ms 12040 KB Output is correct
62 Correct 5 ms 11988 KB Output is correct
63 Correct 203 ms 35064 KB Output is correct
64 Correct 8 ms 13396 KB Output is correct
65 Correct 15 ms 17364 KB Output is correct
66 Correct 126 ms 60528 KB Output is correct
67 Correct 545 ms 99220 KB Output is correct
68 Correct 592 ms 101204 KB Output is correct
69 Correct 11 ms 12980 KB Output is correct
70 Correct 79 ms 21812 KB Output is correct
71 Correct 252 ms 43848 KB Output is correct
72 Correct 279 ms 42664 KB Output is correct
73 Correct 69 ms 19548 KB Output is correct
74 Correct 456 ms 39624 KB Output is correct
75 Correct 24 ms 15460 KB Output is correct
76 Correct 272 ms 43652 KB Output is correct
77 Correct 258 ms 43548 KB Output is correct
78 Correct 33 ms 19564 KB Output is correct
79 Correct 576 ms 90560 KB Output is correct
80 Correct 8 ms 12244 KB Output is correct
81 Correct 67 ms 21964 KB Output is correct
82 Correct 343 ms 41428 KB Output is correct
83 Correct 392 ms 39596 KB Output is correct
84 Correct 342 ms 39560 KB Output is correct
85 Correct 352 ms 39616 KB Output is correct
86 Correct 341 ms 40708 KB Output is correct
87 Correct 333 ms 40692 KB Output is correct