Submission #235831

#	Time	Username	Problem	Language	Result	Execution time	Memory
235831		balbit	Beads and wires (APIO14_beads)	C++14	0 / 100	37 ms	5120 KiB

beads

#include <bits/stdc++.h>
using namespace std;


#define ll long long

#define int ll

#define pii pair<int, int>
#define f first
#define s second

#define REP(i,n) for (int i = 0; i<n; ++i)
#ifdef BALBIT
#define bug(...) cerr<<"#"<<__LINE__<<": "<<#__VA_ARGS__<<": ", _do(__VA_ARGS__)
template<typename T> void _do(T && x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y){cerr<<x<<", "; _do(y...);}
#define IOS()
#else
#define IOS() ios::sync_with_stdio(0), cin.tie(0)
#define endl '\n'
#define bug(...)
#endif // BALBIT

#define SZ(x) (int)(x.size())
#define ALL(x) (x).begin(), (x).end()
#define pb push_back
const int maxn = 2e5+5;
vector<pii> g[maxn];
ll dp[maxn][2];

void dfs(int v, int p, ll w) {
    vector<ll> mo;
    ll sg = 0;
    for (pii u : g[v]) {
        if (u.f != p) {
            dfs(u.f,v,u.s);
            mo.pb(dp[u.f][0] - dp[u.f][1] + u.s);
            sg += dp[u.f][1];
        }
    }
    sort(ALL(mo), greater<ll>());
    dp[v][0] = sg;
    if (SZ(mo) >= 2) {
        dp[v][0] = max(dp[v][0], sg + mo[0] + mo[1]);
    }
    dp[v][1] = dp[v][0];
    if (SZ(mo) >= 1) {
        dp[v][1] = max(dp[v][1], sg + mo[0] + w);
    }
}

signed main(){
    IOS();

    int n; cin>>n;
    if (n <= 2) assert(0);
    vector<pair<pii, int> > v;
    for (int i = 0; i<n-1; ++i) {
        int a,b,w; cin>>a>>b>>w;
        v.pb({{a,b},w});
        --a;--b;g[a].pb({b,w});g[b].pb({a,w});
    }
    sort(ALL(v));
    ll re = 0;
    do{
        vector<int> done(n);
        bool ok = 1;
        ll s = 0;
        for (int i = 0; i<SZ(v); i+=2){
            if (v[i].f.f == v[i+1].f.f || v[i].f.f == v[i+1].f.s) {
                if (!done[v[i].f.f]) s += v[i].s + v[i+1].s;
                 done[v[i].f.f] = 1;
            }else{
                if (v[i].f.s == v[i+1].f.f || v[i].f.s == v[i+1].f.s) {
                    if (!done[v[i].f.s]) s += v[i].s + v[i+1].s;
                    done[v[i].f.s] = 1;
                }
            }
        }
        re = max(re, s);
    }while (next_permutation(ALL(v)));
    cout<<re<<endl;
//    dfs(0,-1,0);
//    cout<<dp[0][0]<<endl;

}
/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:68:14: warning: unused variable 'ok' [-Wunused-variable]
         bool ok = 1;
              ^~

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