제출 #537232

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
537232		Lobo	Beads and wires (APIO14_beads)	C++17	0 / 100	3 ms	5460 KiB

beads

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

const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()

#define maxn 220000

int n, dp[maxn][4], mark[maxn][4], a[maxn], b[maxn], c[maxn];
vector<pair<int,int>> g[maxn];

int sol(int u, int p, int ant) {
    if(mark[u][p]) return dp[u][p];
    mark[u][p] = 1;

    if(p == 0) {
        //o pai liga para ele, entao pode ligar para 2 com 
        //aresta azul, para 1 com aresta vermelha ou para nenhum

        //liga para nenhum/todos ligam para ele
        int ans0 = 0;
        for(auto V : g[u]) {
            int v = V.fr;
            int w = V.sc;
            if(v == ant) continue;

            ans0+= max(sol(v,1,u),sol(v,2,u)+w);
        }

        //liga para 1 com aresta vermelha
        
        int mx1 = -inf;
        for(auto V : g[u]) {
            int v = V.fr;
            int w = V.sc;
            if(v == ant) continue;

            mx1 = max(mx1, sol(v,0,u) - max(sol(v,1,u),sol(v,2,u)+w));
        }
        int ans1 = ans0+mx1;

        //liga para 2 com aresta azul
        pair<int,int> mx2 = mp(-inf,-inf);
        for(auto V : g[u]) {
            int v = V.fr;
            int w = V.sc;
            if(v == ant) continue;

            mx2.sc = max(mx2.sc, w + sol(v,0,u) - max(sol(v,1,u),sol(v,2,u)+w));
            if(mx2.sc > mx2.fr) swap(mx2.sc,mx2.fr);
        }

        int ans2 = ans0 + mx2.fr + mx2.sc;

        return dp[u][p] = max({ans0,ans1,ans2});
    }
    else if(p == 1) {
        //p = 1, liga dele pro pai com red
        int ans = 0;
        //todos tem que ligar deles para o u
        for(auto V : g[u]) {
            int v = V.fr;
            int w = V.sc;
            if(v == ant) continue;

            ans+= max(sol(v,1,u),sol(v,2,u)+w);
        }
        return dp[u][p] = ans;
    }
    else {
        int mx = -inf;
        int ans = 0;
        for(auto V : g[u]) {
            int v = V.fr;
            int w = V.sc;
            if(v == ant) continue;

            ans+= max(sol(v,1,u),sol(v,2,u)+w);
            mx = max(mx, w +sol(v,0,u) - max(sol(v,1,u),sol(v,2,u)+w));
        }

        return dp[u][p] = ans+mx;
    }
}

void solve() {
    cin >> n;

    for(int i = 1; i < n; i++) {
        cin >> a[i] >> b[i] >> c[i];
        g[a[i]].pb(mp(b[i],c[i]));
        g[b[i]].pb(mp(a[i],c[i]));
    }

    int rt;
    for(int i = 1; i <= n; i++) {
        if(g[i].size() == 1) {
            rt = i;
            break;
        }
    }

    cout << sol(rt,0,0) << endl;

}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(0);

    // freopen("in.in", "r", stdin);
    // freopen("out.out", "w", stdout);

    int tt = 1;
    // cin >> tt;
    while(tt--) solve();

}

컴파일 시 표준 에러 (stderr) 메시지

beads.cpp: In function 'void solve()':
beads.cpp:103:9: warning: 'rt' may be used uninitialized in this function [-Wmaybe-uninitialized]
  103 |     int rt;
      |         ^~

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