Submission #198925

#	Time	Username	Problem	Language	Result	Execution time	Memory
198925		red1108	Beads and wires (APIO14_beads)	C++17	100 / 100	335 ms	41064 KiB

beads

#include<bits/stdc++.h>
#include<ext/rope>
using namespace std;
using namespace __gnu_cxx;
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false);cin.tie(0)
#define fopen freopen("input.txt", "r", stdin)
#define eb emplace_back
#define em emplace
#define prec(a) cout<<fixed;cout.precision(a);
#define all(a) (a).begin(), (a).end()
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> tiii;
const ll INF = 2e16;
const ll inf = 2e9;
template<class T>
void pr(T t) {cout << t << " ";}
template<class T, class ...Args>
void pr(T a, Args ...args) {cout << a << " ";pr(args...);}
template<class ...Args>
void prl(Args ...args) {pr(args...);cout << endl;}
 
int n;
const int MAXN=200010;
vector<pll> tree[MAXN];
ll dp1[MAXN],dp2[MAXN],dp3[MAXN],dp4[MAXN],ans;
void dfs(int x, int par, ll bac){
	dp2[x]=dp3[x]=dp4[x]=-inf;
	ll sum=0;
	vector<pll> h1,h3,h4,hh;
	int c=0;
	for(auto i:tree[x]) if(i.fi!=par){
		dfs(i.fi,x,i.se);
		ll tmp = max(dp1[i.fi], dp2[i.fi]);
		dp1[x]+=tmp;
		sum+=tmp;
		c++;
		h1.eb(dp1[i.fi]+i.se-tmp,i.fi);
		h3.eb(dp3[i.fi]+i.se-tmp,i.fi);
		h4.eb(max(dp3[i.fi]+i.se,dp4[i.fi])-tmp,i.fi);
		hh.eb(max(dp3[i.fi],dp4[i.fi])-tmp,i.fi);
	}
	sort(all(h1));reverse(all(h1));
	sort(all(h3));reverse(all(h3));
	sort(all(h4));reverse(all(h4));
	sort(all(hh));reverse(all(hh));
	if(c>=1){
		dp2[x] = max(dp2[x],sum + h1[0].fi + bac);
		dp4[x] = max(dp4[x],sum + h3[0].fi + bac);
		dp3[x] = max(dp3[x],sum + hh[0].fi);
	}
	if(c>=2){
		for(int i=0;i<2;i++)
			for(int j=0;j<2;j++)
				if(h1[i].se!=h3[j].se)
					dp3[x] = max(dp3[x], sum + h1[i].fi+h3[j].fi);
		dp3[x] = max(dp3[x], sum + h1[0].fi+h1[1].fi);
	}
}
int main(){
	fastio;
	cin>>n;
	for(int i=1;i<n;i++){
		int a, b, c;cin>>a>>b>>c;
		tree[a].eb(b,c);
		tree[b].eb(a,c);
	}
	dfs(1,0,0);
	cout<<max(dp1[1],dp3[1]);
}

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