Submission #42021

#	Time	Username	Problem	Language	Result	Execution time	Memory
42021		cmaster	Beads and wires (APIO14_beads)	C++14	0 / 100	12 ms	12032 KiB

beads

#include <bits/stdc++.h>
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>*/
 
#define pb push_back
#define mp make_pair
#define sz(s) ((int)(s.size()))
#define all(s) s.begin(), s.end()
#define rep(i, a, n) for (int i = a; i <= n; ++i)
#define per(i, n, a) for (int i = n; i >= a; --i)
#define onlycin ios_base::sync_with_stdio(false); cin.tie(0) 
#define F first
#define S second
using namespace std;
// using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
/*typedef tree<
pair < int, int >,
null_type,
less< pair < int, int > >,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;*/
// find_by_order() order_of_key()
const int MAXN = (int)5e5+228;
const char nxtl = '\n';
const int mod = (int)1e9+7;
const double eps = (double)1e-7;
template<typename T> inline bool updmin(T &a, const T &b) {return a > b ? a = b, 1 : 0;}
template<typename T> inline bool updmax(T &a, const T &b) {return a < b ? a = b, 1 : 0;}

int n, dp[2][MAXN];
vector < pair < int, int > > g[MAXN];

void dfs(int v, int D = 0, int pr = -1) {
	dp[0][v] = dp[1][v] = 0;
	vector < pair < int, int > > child;
	for(auto &it : g[v]) {
		int to = it.F;
		if(pr == to) continue;
		dfs(to, it.S, v);
		child.pb({to, it.S});
	}
	// update dp[1]
	if(pr != -1) {
		int sum0 = 0;
		for(auto &to : child) sum0 += max(dp[0][to.F], dp[1][to.F]);
		for(auto &to : child) {
			sum0 -= max(dp[0][to.F], dp[1][to.F]);
			updmax(dp[1][v], sum0+D+to.S+dp[0][to.F]);
			sum0 += max(dp[0][to.F], dp[1][to.F]);
		}
	}
	// update dp[0]
	for(auto &to : child) {
		for(auto &it : child) {
			if(to.F == it.F) continue;
			int sum = 0;
			for(auto &k : child) {
				if(k.F == to.F || k.F == it.F) continue;
				sum += max(dp[0][k.F], dp[1][k.F]);
			}
			updmax(dp[0][v], sum + to.S + it.S + dp[0][to.F] + dp[0][it.F]);
		}
	}
	cerr << v << ' '<< dp[0][v] << ' '<< dp[1][v] << nxtl;
}

int main() {
	#ifdef accepted
		freopen(".in", "r", stdin);
		freopen(".out", "w", stdout);
	#endif
	onlycin;
	cin >> n;
	rep(i, 2, n) {
		int x, y, z; cin >> x >> y >> z;
		g[x].pb(mp(y, z)); g[y].pb(mp(x, z));
	}
	dfs(1);
	int res = dp[0][1];
	rep(root, 2, n) {
		dfs(root);
		updmax(res, dp[0][root]);
	}
	cout << res << nxtl;
	
	return 0;
}

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