Submission #263100

#	Time	Username	Problem	Language	Result	Execution time	Memory
263100		blackyuki	Beads and wires (APIO14_beads)	C++14	100 / 100	549 ms	37352 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) {sort(all(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;}

ll dp[2][2][200005];
vvp g;

void dfs(int i,int p,ll e){
    ll sum=0,mx=-inf,my=-inf;
    vp v,u;
    for(auto x:g[i])if(x.fi!=p){
        dfs(x.fi,i,x.se);
        sum+=dp[1][0][x.fi];
        v.pb(dp[0][1][x.fi]-dp[1][0][x.fi]+x.se,x.fi);
        u.pb(dp[1][1][x.fi]-dp[1][0][x.fi]+x.se,x.fi);
        chmax(mx,dp[0][0][x.fi]-dp[1][0][x.fi]);
    }
    sort(all(v));reverse(all(v));
    sort(all(u));reverse(all(u));
    if(v.size()>1){
        if(v[0].se!=u[0].se)dp[0][1][i]=sum+v[0].fi+u[0].fi;
        chmax(dp[0][1][i],sum+v[0].fi+u[1].fi);
        chmax(dp[0][1][i],sum+u[0].fi+v[1].fi);
    }
    if(v.size())dp[0][0][i]=sum+v[0].fi+e;
    if(u.size())chmax(dp[1][0][i],sum+u[0].fi+e);
    chmax(dp[0][1][i],sum+mx);
    dp[1][1][i]=sum;
    for(int j=1;j>=0;j--)for(int k=1;k>=0;k--){
        if(j)chmax(dp[j-1][k][i],dp[j][k][i]);
        if(k)chmax(dp[j][k-1][i],dp[j][k][i]);
    }
    // out(i);rep(j,2)rep(k,2)cout<<dp[j][k][i]<<' ';cout<<endl;
}

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);
    }
    dfs(0,-1,-inf);
    out(dp[0][1][0]);
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int, ll)':
beads.cpp:58:22: warning: unused variable 'my' [-Wunused-variable]
   58 |     ll sum=0,mx=-inf,my=-inf;
      |                      ^~

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