Submission #197722

#	Time	Username	Problem	Language	Result	Execution time	Memory
197722		moonrabbit2	Beads and wires (APIO14_beads)	C++17	0 / 100	7 ms	5112 KiB

beads

#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<db,db> pdb;
typedef tuple<int,int,int> tii;
typedef vector<vector<ll>> mat;
const ll mod=1e9+7;
const int N=2e5+5;
int n,ans,dp1[N],dp2[N],dp3[N];
vector<pii> g[N];
void dfs(int x,int p){
    vector<int> v;
    for(auto &it : g[x]) if(it.fi!=p){
        int u=it.fi,c=it.se;
        dfs(u,x);
        v.emplace_back(max(dp1[u],dp2[u])+c-max({dp1[u],dp2[u],dp3[u]+c}));
        dp1[x]+=max({dp1[u],dp2[u],dp3[u]+c});
    }
    sort(v.begin(),v.end()); reverse(v.begin(),v.end());
    if(v.size()>=2){
        dp2[x]=dp1[x]+v[0]+v[1];
    } else dp2[x]=-1e9;
    if(v.size()>=1&&p){
        dp3[x]=dp1[x]+v[0];
    } else dp3[x]=-1e9;
}
int main(){
    ios::sync_with_stdio(false); cin.tie(0);
	cin>>n;
    for(int u,v,c,i=1;i<n;i++){
        cin>>u>>v>>c;
        g[u].emplace_back(v,c);
        g[v].emplace_back(u,c);
    }
    dfs(1,0);
    cout<<max({dp1[1],dp2[1],dp3[1]});
    return 0;
}

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