Submission #412735

#	Time	Username	Problem	Language	Result	Execution time	Memory
412735		LastRonin	Beads and wires (APIO14_beads)	C++14	0 / 100	1 ms	460 KiB

beads

#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define ll long long
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define pill pair<ll, ll>
using namespace std;

const ll N = 1e4 + 10;
const ll big = 1e9;
 
ll n;
vector<pair<int,int>> g[N];
int p[N], str[N], zn[N], dp2[N][3], cnt = 1;
int ans;
 
int main() {
	speed;
	cin >> n;
	for(int i = 1, a, b, c; i < n; i++)
		cin >> a >> b >> c, g[a].pb(mp(b, c)), g[b].pb(mp(a, c));
	for(int i = 1; i <= n; i++) {
		str[0] = i;
		cnt = 1;
		p[i] = 0;
		for(int j = 0; j < n; j++) {
		    dp2[j + 1][0] = 0, dp2[j + 1][1] = dp2[j + 1][2] = -big;
			for(auto u : g[str[j]]) {
				if(p[str[j]] != u.f) {
					str[++cnt] = u.f, p[u.f] = str[j],zn[u.f] = u.s;
				}
			}
		}         
		for(int j = n - 1; j >= 0; j--) {
			int v = str[j], pp = p[v];
			int z = max(dp2[v][0], dp2[v][1] + zn[v]); 
			dp2[pp][2] = max(dp2[pp][2] + z, dp2[pp][1] + dp2[v][0] + zn[v]);
			dp2[pp][1] = max(dp2[pp][1] + z, dp2[pp][0] + dp2[v][0] + zn[v]);
			dp2[pp][0] = dp2[pp][0] + z;
			ans = max(ans, dp2[v][2]);
		}
	}
	cout << ans;
}
/*
10
5 6 9
2 3 5
1 10 8
4 5 9
2 7 8
5 7 10
6 9 4
2 8 9
1 7 5
 
 
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
 
*/

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