Submission #670194

#	Time	Username	Problem	Language	Result	Execution time	Memory
670194		NothingXD	Beads and wires (APIO14_beads)	C++17	100 / 100	250 ms	27472 KiB

beads

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

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
/*typedef __uint128_t L;
struct FastMod {
  ull b, m;
  FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
  ull reduce(ull a) {
    ull q = (ull)((L(m) * a) >> 64);
    ull r = a - q * b; // can be proven that 0 <= r < 2*b
    return r >= b ? r - b : r;
  }
};
FastMod FM(2);*/
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
	cerr << " " << H;
	debug_out(T...);
}

#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 2e5 + 10;
const int inf = 2e9;

int n, dp[maxn][2][2]; // 0 ya 1 aval mitone root bezane? 0 ya 1 dovom yal parentesh khalie ya na
vector<pii> g[maxn];

void dfs(int v, int p = -1, int x = 0){
	int mx = 0;
	for (auto [u, w]: g[v]){
		if (u != p){
			dfs(u, v, w);
			dp[v][0][0] += dp[u][0][1];
			dp[v][0][1] += dp[u][0][1];
			dp[v][1][0] += dp[u][0][1];
			dp[v][1][1] += dp[u][0][1];
			mx = max(mx, dp[u][1][1] - dp[u][0][1]);
		}
	}
	dp[v][1][0] += mx;
	dp[v][1][1] += mx;
	if (p != -1 && g[v].size() != 1){
		int tmp = x;
		int mx = -inf;
		for (auto [u, w]: g[v]){
			if (u != p){
				tmp += dp[u][0][1];
				mx = max(mx, dp[u][0][0] - dp[u][0][1] + w);
			}
		}
		dp[v][0][1] = max(dp[v][0][1], tmp + mx);
		tmp = x;
		mx = -inf;
		for (auto [u, w]: g[v]){
			if (u != p){
				tmp += dp[u][0][1];
				mx = max(mx, dp[u][1][0] - dp[u][0][1] + w);
			}
		}
		dp[v][1][1] = max(dp[v][1][1], tmp + mx);
	}
	if ((int)g[v].size() - (p != -1) >= 2){
		multiset<int> st;
		int tmp = 0;
		int mx = 0;
		for (auto [u, w]: g[v]){
			if (u != p){
				tmp += dp[u][0][1];
				st.insert(dp[u][0][0] - dp[u][0][1] + w);
			}
		}
		for (auto [u, w]: g[v]){
			if (u != p){
				st.erase(st.find(dp[u][0][0] - dp[u][0][1] + w));
				auto it = st.end();
				it--;
				int x = *it;
				mx = max(mx, tmp + x + dp[u][1][0] - dp[u][0][1] + w);
				st.insert(dp[u][0][0] - dp[u][0][1] + w);
			}
		}
		dp[v][1][0] = max(dp[v][1][0], mx);
		dp[v][1][1] = max(dp[v][1][1], mx);
	}
}

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);

	cin >> n;

	for (int i = 1; i < n; i++){
		int u, v, w; cin >> u >> v >> w;
		g[u].push_back({v, w});
		g[v].push_back({u, w});
	}

	dfs(1);

	cout << dp[1][1][0] << '\n';

	return 0;
}

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