Submission #362957

#	Time	Username	Problem	Language	Result	Execution time	Memory
362957		ijxjdjd	Beads and wires (APIO14_beads)	C++14	0 / 100	5 ms	5100 KiB

beads

#include <bits/stdc++.h>
#define FR(i, N) for (int i = 0; i < int(N); i++)
#define all(x) begin(x), end(x)

#define f first
#define s second
using namespace std;

using ll = long long;

const int MAXN = (int)(2e5) + 5;
vector<pair<int, int>> adj[MAXN];
int dp[MAXN][2];

void dfs(int n, int p, int w) {
    vector<int> tot;
    int allSum = 0;
    for (auto& e : adj[n]) {
        if (e.f != p) {
            dfs(e.f, n, e.s);
            tot.push_back(e.s + dp[e.f][0] - dp[e.f][1]);
            allSum += dp[e.f][1];
        }
    }
    sort(all(tot));
    reverse(all(tot));
    dp[n][0] = allSum;
    dp[n][1] = allSum;
    for (int i = 0; i < min(2, int(tot.size())); i++) {
        allSum += tot[i];
        if (i%2 == 0) {
            dp[n][1] = max(dp[n][1], allSum + w);
        }
        else {
            dp[n][0] = max(dp[n][0], allSum);
        }
    }
    dp[n][1] = max(dp[n][1], dp[n][0]);
}

int main() {
	cin.tie(0);
	cin.sync_with_stdio(0);
	int N;
	cin >> N;
	FR(i, N-1) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
	}
	dfs(0, 0, 0);
	cout << dp[0][0] << '\n';
	return 0;
}

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