Submission #372714

#	Time	Username	Problem	Language	Result	Execution time	Memory
372714		hivakarami	Beads and wires (APIO14_beads)	C++14	13 / 100	12 ms	14444 KiB

beads

#include<bits/stdc++.h>
 
using namespace std;
 
typedef long long int ll;
typedef long double ld;
#define f first
#define s second
 
const int N = 2e5 + 100;
const ll mod = 998244353;
const ll inf = 1e9 + 100;

ll dp[4][N], par[N], ans = 0, e[N];
vector<pair<ll, ll>> adj[N];
set<ll> st[N];
int n;


inline void upd(int u)
{
	dp[1][u] = dp[0][u];
	if(st[u].size())
	{
		ll w = *(st[u].rbegin());
		dp[1][u] += max(0ll, w + e[u]);
	}
}


void dfs(int u)
{
	for(auto it : adj[u])
	{
		int x = it.f;
		ll w = it.s;
		if(x != par[u])
		{
			par[x] = u;
			e[x] = w;
			dfs(x);
			dp[0][u] += dp[1][x];
			st[u].insert(dp[0][x] - dp[1][x] + e[x]);
		}
	}
	
	upd(u);
	
	//cout << u << ' ' << dp[1][u] << ' ' << dp[2][u] << endl;
}

inline void move_root(int x, int u, ll w)
{
	st[x].erase(dp[0][u]-dp[1][u]+w);
	dp[0][x] -= dp[1][u];
	e[x] = w;
	upd(x);
	
	e[u] = 0;
	dp[0][u] += dp[1][x];
	st[u].insert(dp[0][x]-dp[1][x]+e[x]);
	upd(u);
	
}



void DFS(int u)
{
	ans = max(ans, dp[0][u]);
	for(auto it : adj[u])
	{
		int x = it.f;
		ll w = it.s;
		if(x == par[u])
			continue;
		move_root(u, x, w);
		DFS(x);
		move_root(x, u, w);
	
	}
}





int main()
{
    ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);	
	
	cin >> n;
	for(int i = 0; i < n-1; i++)
	{
		int x, y;
		ll w;
		cin >> x >> y >> w;
		x--; y--;
		adj[x].push_back({y, w});
		adj[y].push_back({x, w});
	}
	
	
	dfs(0);
	
	DFS(0);
		
	cout << ans << endl;
	
	
		
		
	return 0;
}

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