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답안 #735206

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
735206 2023-05-03T17:28:15 Z vjudge1 구슬과 끈 (APIO14_beads) C++17
57 / 100
 322 ms 18228 KB 
#include <bits/stdc++.h>
using namespace std;

int main() {
        int n;
        cin >> n;
        if (n <= 2) return cout << 0, 0;
        vector<vector<pair<int, int>>> adj(n);
        for (int i = 0; i < n - 1; i++) {
                int a, b, c;
                cin >> a >> b >> c;
                a--, b--;
                adj[a].emplace_back(b, c);
                adj[b].emplace_back(a, c);
        }
        vector<vector<int>> f(2, vector<int>(n, 0));
        function<void(int, int)> dfs = [&](int u, int p) {
                f[1][u] = -2e9;
                f[0][u] = 0;
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first;
                        int c = e.second;
                        if (v == p) continue;
                        dfs(v, u);
                        f[0][u] += max(f[0][v], f[1][v] + c);
                }
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first;
                        int c = e.second;
                        if (v == p) continue;
                        f[1][u] = max(f[1][u], f[0][u] - max(f[0][v], f[1][v] + c) + f[0][v] + c);
                }
        };

        int res = 0;

        function<void(int, int)> reroot = [&](int u, int p) {
                // re-calc f[u]
                int ff0 = f[0][u];
                int ff1 = f[1][u];
                f[0][u] = 0;
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first, c = e.second;
                        f[0][u] += max(f[0][v], f[1][v] + c);
                }
                vector<int> bestf(2, -2e9);
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first, c = e.second;
                        bestf.emplace_back(f[0][u] - max(f[0][v], f[1][v] + c) + f[0][v] + c);
                        int i = bestf.size() - 1;
                        while (i > 0 && bestf[i] > bestf[i - 1]) swap(bestf[i], bestf[i - 1]), i--;
                        bestf.pop_back();
                }
                f[1][u] = bestf[0];
                // update result
                vector<int> best;
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first, c = e.second;
                        best.emplace_back(f[0][v] + c - max(f[0][v], f[1][v] + c));
                        int i = best.size() - 1;
                        while (i > 0 && best[i] > best[i - 1]) swap(best[i], best[i - 1]), i--;
                        if (best.size() > 2) best.pop_back();
                }
                if (best.size() == 2) res = max(res, f[0][u] + max(0, best[0] + best[1]));
                // move to the next one

                for (pair<int, int>& e : adj[u]) {
                        int v = e.first, c = e.second;
                        if (v == p) continue;
                        int f0 = f[0][u];
                        f[0][u] -= max(f[0][v], f[1][v] + c);
                        f[1][u] = bestf[0] == (f[0][u] + f[0][v] + c) ? bestf[1] : bestf[0];
                        f[1][u] -= max(f[0][v], f[1][v] + c);
                        reroot(v, u);
                        f[1][u] = bestf[0];
                        f[0][u] = f0;
                }
                f[0][u] = ff0;
                f[1][u] = ff1;
        };

        dfs(0, -1);
        reroot(0, -1);

        cout << res;
}

Subtask #1
13.0 / 13.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 300 KB Output is correct
12 Correct 1 ms 212 KB Output is correct

Subtask #2
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 300 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 300 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 300 KB Output is correct

Subtask #3
29.0 / 29.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 300 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 300 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 300 KB Output is correct
23 Correct 6 ms 700 KB Output is correct
24 Correct 8 ms 688 KB Output is correct
25 Correct 8 ms 712 KB Output is correct
26 Correct 16 ms 1112 KB Output is correct
27 Correct 12 ms 1108 KB Output is correct
28 Correct 10 ms 1204 KB Output is correct
29 Correct 10 ms 1108 KB Output is correct
30 Correct 11 ms 1212 KB Output is correct
31 Correct 11 ms 2004 KB Output is correct

Subtask #4
0 / 43.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 300 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 300 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 300 KB Output is correct
23 Correct 6 ms 700 KB Output is correct
24 Correct 8 ms 688 KB Output is correct
25 Correct 8 ms 712 KB Output is correct
26 Correct 16 ms 1112 KB Output is correct
27 Correct 12 ms 1108 KB Output is correct
28 Correct 10 ms 1204 KB Output is correct
29 Correct 10 ms 1108 KB Output is correct
30 Correct 11 ms 1212 KB Output is correct
31 Correct 11 ms 2004 KB Output is correct
32 Correct 60 ms 4584 KB Output is correct
33 Correct 69 ms 4624 KB Output is correct
34 Correct 63 ms 4632 KB Output is correct
35 Incorrect 322 ms 18228 KB Output isn't correct
36 Halted 0 ms 0 KB -