Submission #569744

#	Time	Username	Problem	Language	Result	Execution time	Memory
569744		SSRS	Beads and wires (APIO14_beads)	C++14	0 / 100	1 ms	212 KiB

beads

#include <bits/stdc++.h>
using namespace std;
const int INF = 2000000000;
int main(){
  int n;
  cin >> n;
  vector<vector<pair<int, int>>> E(n);
  for (int i = 0; i < n - 1; i++){
    int a, b, c;
    cin >> a >> b >> c;
    a--;
    b--;
    E[a].push_back(make_pair(c, b));
    E[b].push_back(make_pair(c, a));
  }
  vector<int> p(n, -1);
  vector<vector<pair<int, int>>> c(n);
  queue<int> Q;
  Q.push(0);
  vector<int> bfs;
  while (!Q.empty()){
    int v = Q.front();
    Q.pop();
    bfs.push_back(v);
    for (auto P : E[v]){
      int w = P.second;
      if (w != p[v]){
        p[w] = v;
        c[v].push_back(P);
        Q.push(w);
      }
    }
  }
  reverse(bfs.begin(), bfs.end());
  vector<int> dp1(n, 0);
  vector<int> dp2(n, -INF);
  for (int v : bfs){
    int cnt = c[v].size();
    vector<vector<int>> dp3(3, vector<int>(cnt + 1, -INF));
    dp3[0][0] = 0;
    for (int i = 0; i < cnt; i++){
      int l = c[v][i].first;
      int w = c[v][i].second;
      for (int j = 0; j < 3; j++){
        dp3[j][i + 1] = max(dp3[j][i + 1], dp3[j][i] + max(dp1[w], dp2[w] + l));
        if (j < 2){
          dp3[j + 1][i + 1] = max(dp3[j + 1][i + 1], dp3[j][i] + dp1[w] + l);
        }
      }
    }
    dp1[v] = max(dp3[0][cnt], dp3[2][cnt]);
    dp2[v] = dp3[1][cnt];
  }
  cout << dp1[0] << endl;
}

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