Submission #135081

#	Time	Username	Problem	Language	Result	Execution time	Memory
135081		fredbr	Beads and wires (APIO14_beads)	C++17	28 / 100	1044 ms	1144 KiB

beads

#include <bits/stdc++.h>

#pragma GCC optimize("O3")

using namespace std;

int const maxn = 10001;

struct Edge {
    int u, w;
};

vector<Edge> v[maxn];

int dp[maxn][2];

inline int invalid(int x, int p) {
    return v[x].size() == 1 and v[x].front().u == p;
}

int solve(int x, int p = -1, int t = 0) {
    if (dp[x][t] >= 0) return dp[x][t];

    int d = 0;

    if (t == 0) {
        for (Edge const& e : v[x]) {
            if (e.u == p) continue;

            if (!invalid(e.u, x)) {
                d += max(solve(e.u, x, 1) + e.w, solve(e.u, x, 0));
            }
        }
    }
    else {
        int sum = solve(x, p, 0);

        for (Edge const& e : v[x]) {
            if (e.u == p) continue;

            if (!invalid(e.u, x))
                d = max(d, sum - max(solve(e.u, x, 1) + e.w, solve(e.u, x, 0))
                           + e.w + solve(e.u, x, 0));
            else
                d = max(d, sum + e.w);
        }
    }

    return dp[x][t] = d;
}

inline int test(int x) {
    memset(dp, -1, sizeof(dp));

    return solve(x);
}

int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);

    int n;
    cin >> n;

    for (int i = 0; i < n-1; i++) {
        int a, b, w;
        cin >> a >> b >> w;

        v[a].push_back({b, w});
        v[b].push_back({a, w});
    }

    int ans = 0;
    for (int i = 1; i <= n; i++)
        if (v[i].size() == 1)
            ans = max(ans, test(i));

    cout << ans << "\n";
}

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43