제출 #198242

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
198242		alishahali1382	구슬과 끈 (APIO14_beads)	C++14	28 / 100	1082 ms	5216 KiB

beads

#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const ld eps=1e-7;
const int inf=2000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 200010, LOG=20;

int n, m, k, u, v, x, y, t, a, b, ans;
int dp[MAXN][2];
vector<pii> G[MAXN];

void dfs(int node, int par){
	dp[node][0]=0;
	dp[node][1]=-inf;
	for (pii p:G[node]) if (p.first!=par) dfs(p.first, node);
	
	int sum=0;
	for (pii p:G[node]) if (p.first!=par) sum+=max(dp[p.first][0], dp[p.first][1]+p.second);
	dp[node][0]=sum;
	
	for (pii p:G[node]) if (p.first!=par) dp[node][1]=max(dp[node][1], sum+min(p.second, dp[p.first][0]-dp[p.first][1]));
	
	//dp[node][0]=sum;
	
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	cin>>n;
	assert(n<=10000);
	for (int i=1; i<n; i++){
		cin>>u>>v>>x;
		G[u].pb({v, x});
		G[v].pb({u, x});
	}
	/*
	dfs(4, 4);
	for (int i=1; i<=n; i++){
		debug(i)
		debug2(dp[i][0], dp[i][1])
		cerr<<'\n';
	}
	*/
	//return 0;
	
	
	for (int i=1; i<=n; i++){
		for (int j=1; j<=n; j++) dp[j][0]=0, dp[j][1]=-inf;
		dfs(i, i);
		ans=max(ans, dp[i][0]);
		//debug2(i, dp[i][0])
	}
	cout<<ans<<'\n';
	
	return 0;
}
/*
5
1 2 10
1 3 40
1 4 15
1 5 20

*/

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