Submission #666098

#	Time	Username	Problem	Language	Result	Execution time	Memory
666098		AmirAli_H1	Beads and wires (APIO14_beads)	C++17	0 / 100	3 ms	5076 KiB

beads

// In the name of Allah

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

typedef long long int	ll;
typedef long double	ld;
typedef pair<int, int>	pii;
typedef pair<ll, ll>	pll;

#define all(x)		(x).begin(),(x).end()
#define len(x)		((ll) (x).size())
#define F		first
#define S		second
#define pb		push_back
#define sep             ' '
#define endl            '\n'
#define Mp		make_pair
#define debug(x)	cerr << #x << ": " <<  x << endl;
#define kill(x)		cout << x << '\n', exit(0);
#define set_dec(x)	cout << fixed << setprecision(x);
#define file_io(x,y)	freopen(x, "r", stdin); freopen(y, "w", stdout);

int n;
const int maxn = 2e5 + 5;
const int oo = 1e9;
vector<pll> adj[maxn];
ll dp[maxn][3];
bool mark[maxn];

void dfs(int v, ll x = -1) {
	mark[v] = 1;
	vector<ll> ls1, ls2;
	ll res1 = 0, res2 = 0;
	for (auto f : adj[v]) {
		int u = f.F; ll w = f.S;
		if (!mark[u]) {
			dfs(u, w);
			res1 += max(dp[u][1], dp[u][2]); res2 += max(dp[u][1], dp[u][2]);
			dp[v][1] += max(dp[u][1], dp[u][2]);
			dp[v][2] += max(dp[u][1], dp[u][2]);
			ls1.pb((max(dp[u][0], dp[u][1]) + w) - max(dp[u][1], dp[u][2]));
			ls2.pb(dp[u][0] - max(dp[u][1], dp[u][2]));
		}
	}
	sort(all(ls1), greater<ll>()); sort(all(ls2), greater<ll>());
	
	if (len(ls1) >= 2) res1 += (ls1[0] + ls1[1]);
	else res1 = 0;
	if (len(ls2) >= 1) res2 += ls2[0];
	else res2 = 0;
	dp[v][0] = max(res1, res2);
	
	if (len(ls1) >= 1 && x != -1) dp[v][2] += (x + ls1[0]);
	else dp[v][2] = 0;
	
	ls1.clear(); ls2.clear();
}

int main() {
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	
	cin >> n;
	for (int i = 0; i < n - 1; i++) {
		int u, v; ll w;
		cin >> u >> v >> w; u--; v--;
		adj[u].pb(Mp(v, w)); adj[v].pb(Mp(u, w));
	}
	
	dfs(0);
	
	cout << max(dp[0][0], dp[0][1]) << endl;
	
	return 0;
}

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