Submission #851141

#	Time	Username	Problem	Language	Result	Execution time	Memory
851141		ntkphong	Beads and wires (APIO14_beads)	C++14	0 / 100	2 ms	4956 KiB

beads

#include <bits/stdc++.h>
#define int long long
using namespace std;

const int INF = 1e18;
const int mxN = 2e5 + 10;

int n;
vector<vector<pair<int, int>>> adj(mxN);
int dp[mxN][2];

void dfs(int u, int fu) {
    vector<int> g;

    dp[u][0] = 0;
    dp[u][1] = - INF;
    int sum = 0;

    for(auto [v, w] : adj[u]) {
        if(v == fu) continue ;

        dfs(v, u);

        sum += max(dp[v][0], dp[v][1] + w);
        g.push_back((dp[v][0] + w) - max(dp[v][0], dp[v][1] + w));
    }

    sort(g.begin(), g.end(), greater<int> ());

    dp[u][0] = max(dp[u][0], sum);
    if(g.size() > 1) dp[u][0] = max(dp[u][0], sum + g[0] + g[1]);
    if(g.size() > 0) dp[u][1] = max(dp[u][1], sum + g[0]);
}

signed main() {

    cin.tie(0)->sync_with_stdio(0);

    cin >> n;

    for(int i = 1; i <= n - 1; i ++) {
        int u, v, w;
        cin >> u >> v >> w;

        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dfs(1, 1);

    cout << dp[1][0] << "\n";
    return 0;
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(long long int, long long int)':
beads.cpp:19:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   19 |     for(auto [v, w] : adj[u]) {
      |              ^

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