제출 #94908

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
94908		Alexa2001	구슬과 끈 (APIO14_beads)	C++17	0 / 100	14 ms	5120 KiB

beads

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
const ll inf = 1e10;
const int Nmax = 2e5 + 5;

vector< pair<int,int> > v[Nmax];
ll dp[Nmax][2][2], all[5][5], act[5][5];

void init()
{
    int i, j;
    for(i=0; i<=2; ++i)
        for(j=0; j<=1; ++j)
            all[i][j] = -inf;
    all[0][0] = all[0][1] = 0;
}

void dfs(int node, int dad = 0)
{
    int x, i, j, z, w;
    ll up = -inf, cost;

    for(auto it : v[node])
    {
        tie(x, cost) = it;
        if(x == dad)
        {
            up = cost;
            continue;
        }
        dfs(x, node);
    }



    init();
    for(i=0; i<=2; ++i)
        for(j=0; j<=1; ++j)
            act[i][j] = -inf;
    act[0][0] = act[0][1] = 0;

    for(auto it : v[node])
    {
        tie(x, cost) = it;
        if(x == dad) continue;

        for(i=0; i<=2; ++i) /// gradul nodului
            for(j=0; j<=1; ++j) /// am noduri proaste?
                for(z=0; z<=1; ++z)
                    for(w=0; w<=1; ++w)
                        all[i + z][j + w] = max(all[i+z][j+w], act[i][j] + dp[x][z][w]);

        for(i=0; i<=2; ++i)
            for(j=0; j<=1; ++j)
                act[i][j] = all[i][j];
        init();
    }

    dp[node][0][0] = max(act[0][0], act[1][0] + up);
    dp[node][0][1] = max(act[0][1], act[1][1] + up);
    dp[node][0][1] = max(dp[node][0][1], act[2][(node==1)]);


    dp[node][1][0] = act[0][0] + up;
    dp[node][1][1] = max(act[0][1], act[2][0]) + up;
}

int main()
{
 //   freopen("input", "r", stdin);
    cin.sync_with_stdio(false);

    int n, i, x, y, cost;
    cin >> n;
    for(i=1; i<n; ++i)
    {
        cin >> x >> y >> cost;
        v[x].push_back({y, cost});
        v[y].push_back({x, cost});
    }

    dfs(1);
    cout << max(dp[1][0][0], dp[1][0][1]) << '\n';

    return 0;
}

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