Submission #246497

#	Time	Username	Problem	Language	Result	Execution time	Memory
246497		rrrr10000	Beads and wires (APIO14_beads)	C++14	100 / 100	475 ms	32872 KiB

beads

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define dupli(a) a.erase(unique(all(a)),a.end())
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}
vvp g;
vi dfs(int i,int p,ll c){
    vi res(4);
    vp a,b;
    ll ma=0;
    for(auto x:g[i])if(x.fi!=p){
        auto q=dfs(x.fi,i,x.se);
        // out(x.fi);outv(q);
        res[3]+=q[1];
        chmax(ma,q[0]-q[1]);
        a.pb(x.se+q[2]-q[1],x.fi);
        b.pb(x.se+q[3]-q[1],x.fi);
    }
    if(!a.size())return res;
    sort(all(a));reverse(all(a));
    sort(all(b));reverse(all(b));
    rep(j,3)chmax(res[j],res[3]);
    // outvp(a);outvp(b);outv(res);
    chmax(res[0],res[0]+a[0].fi+c);
    chmax(res[1],res[1]+b[0].fi+c);
    res[2]+=ma;
    if(a.size()>1){
        if(a[0].se!=b[0].se)chmax(res[2],res[3]+a[0].fi+b[0].fi);
        else{
            chmax(res[2],res[3]+max(a[0].fi+b[1].fi,a[1].fi+b[0].fi));
        }
    }
    for(int j=2;j>=0;j--){
        chmax(res[j],res[j|1]);
        chmax(res[j],res[j|2]);
    }
    return res;
}
int main(){
    ll n;cin>>n;
    g=vvp(n);
    rep(i,n-1){
        ll a,b,c;cin>>a>>b>>c;a--;b--;
        g[a].pb(b,c);
        g[b].pb(a,c);
    }
    out(dfs(n-1,-1,0)[2]);
}

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