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Submission #735208

# Submission time Handle Problem Language Result Execution time Memory
735208 2023-05-03T17:30:07 Z vjudge1 Beads and wires (APIO14_beads) C++17
100 / 100
 389 ms 33376 KB 
#include <bits/stdc++.h>
using namespace std;

#define int int64_t

int32_t 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] = -1e10;
                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<int>(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<int>(f[1][u], f[0][u] - max<int>(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<int>(f[0][v], f[1][v] + c);
                }
                vector<int> bestf(2, -1e10);
                for (pair<int, int>& e : adj[u]) {
                        int v = e.first, c = e.second;
                        bestf.emplace_back(f[0][u] - max<int>(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<int>(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<int>(res, f[0][u] + max<int>(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<int>(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<int>(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

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 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 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 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 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 0 ms 212 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 0 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 340 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 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 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 0 ms 212 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 0 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 340 KB Output is correct
23 Correct 8 ms 724 KB Output is correct
24 Correct 6 ms 724 KB Output is correct
25 Correct 6 ms 724 KB Output is correct
26 Correct 10 ms 1236 KB Output is correct
27 Correct 11 ms 1236 KB Output is correct
28 Correct 13 ms 1236 KB Output is correct
29 Correct 10 ms 1236 KB Output is correct
30 Correct 11 ms 1144 KB Output is correct
31 Correct 11 ms 2156 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 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 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 0 ms 212 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 0 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 1 ms 340 KB Output is correct
23 Correct 8 ms 724 KB Output is correct
24 Correct 6 ms 724 KB Output is correct
25 Correct 6 ms 724 KB Output is correct
26 Correct 10 ms 1236 KB Output is correct
27 Correct 11 ms 1236 KB Output is correct
28 Correct 13 ms 1236 KB Output is correct
29 Correct 10 ms 1236 KB Output is correct
30 Correct 11 ms 1144 KB Output is correct
31 Correct 11 ms 2156 KB Output is correct
32 Correct 67 ms 5180 KB Output is correct
33 Correct 63 ms 5108 KB Output is correct
34 Correct 58 ms 5112 KB Output is correct
35 Correct 367 ms 19844 KB Output is correct
36 Correct 374 ms 23384 KB Output is correct
37 Correct 389 ms 23452 KB Output is correct
38 Correct 280 ms 22692 KB Output is correct
39 Correct 290 ms 22728 KB Output is correct
40 Correct 336 ms 22692 KB Output is correct
41 Correct 362 ms 33376 KB Output is correct