Submission #305563

#	Time	Username	Problem	Language	Result	Execution time	Memory
305563		MarcoMeijer	Beads and wires (APIO14_beads)	C++14	100 / 100	363 ms	47600 KiB

beads

#include <bits/stdc++.h>
using namespace std;
 
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF (2e9+10)
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
#define sz size()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
 
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
 
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const vector<T>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class T> void OUT(const vector<T>& x) {RE(i,x.size()) OUT(i==0?"":" ",x[i]);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
 
//===================//
//  Added libraries  //
//===================//
 
//===================//
//end added libraries//
//===================//
 
void program();
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    program();
}
 
 
//===================//
//   begin program   //
//===================//
 
const int MX = 6e5+5;

int n, m=0;
int a[MX], b[MX], c[MX];
int rev[MX];
vi adj[MX];
int dp[MX][2];
int sm[MX], skip[MX];
pair<ii,ii> bst[MX];

pair<ii,ii> push(pair<ii,ii> a, ii b) {
    return {max(a.fi,b), max(min(a.fi,b),a.se)};
}

void fillDP(int e);
int getSum(int e) {
    int u = b[e], p = a[e];
    if(sm[u] == -1) {
        sm[u] = 0;
        bst[u] = {{-INF,-1}, {-INF,-1}};
        FOR(v,adj[u]) if(b[v]!=p) fillDP(v), sm[u] += max(dp[v][1]+c[v], dp[v][0]);
        FOR(v,adj[u]) if(b[v]!=p) bst[u] = push(bst[u], {-max(dp[v][1]+c[v], dp[v][0]) + dp[v][0] + c[v], b[v]});
        skip[u] = p;
        return sm[u];
    } else if(skip[u] != -1 && skip[u] != p) {
        FOR(v,adj[u]) if(b[v]==skip[u]) fillDP(v), sm[u] += max(dp[v][1]+c[v], dp[v][0]);
        FOR(v,adj[u]) if(b[v]==skip[u]) bst[u] = push(bst[u], {-max(dp[v][1]+c[v], dp[v][0]) + dp[v][0] + c[v], b[v]});
        skip[u] = -1;
    }
    int res = sm[u];
    if(p != -1 && skip[u] != p) fillDP(rev[e]), res -= max(dp[rev[e]][1]+c[rev[e]], dp[rev[e]][0]);
    return res;
}
void fillDP(int e) {
    if(dp[e][0] != -1) return;

    int u=b[e], p=a[e];
    int sm = getSum(e);
    dp[e][0] = sm;

    dp[e][1] = -2e9-10;
    if(bst[u].fi.se != p) dp[e][1] = max(dp[e][1], sm + bst[u].fi.fi);
    if(bst[u].se.se != p) dp[e][1] = max(dp[e][1], sm + bst[u].se.fi);
}

void program() {
    IN(n);
    RE1(i,n) {
        a[m]=-1;
        b[m]=i;
        c[m]=0;
        m++;
    }
    RE(i,n-1) {
        int u, v, w;
        IN(u,v,w);
        a[m]=u, b[m]=v, c[m]=w;
        rev[m] = m+1;
        adj[u].pb(m++);
        a[m]=v, b[m]=u, c[m]=w;
        rev[m] = m-1;
        adj[v].pb(m++);
    }

    int bst = 0;
    RE(i,m) dp[i][0] = -1;
    RE1(i,n) sm[i] = -1;
    RE(i,n) {
        fillDP(i);
        bst = max(bst, dp[i][0]);
    }
    OUTL(bst);
}

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