Submission #48299

#	Time	Username	Problem	Language	Result	Execution time	Memory
48299		octopuses	Beads and wires (APIO14_beads)	C++17	0 / 100	6 ms	4992 KiB

beads

#include <bits/stdc++.h>

#define ll long long
#define fr first
#define sc second
#define M (ll)(3e17)

using namespace std;
const int N = 200020;

vector < pair < int, int > > G[N];
int n;
ll A[N], B[N];

void go(int v, int p = 0)
{
  ll mx1 = -2e9, mx2 = -2e9, child = 0, tot = 0, par = -2e9;
  for(int i = 0; i < G[v].size(); ++ i)
  {
    int to = G[v][i].first;
    if(to == p)
    {
      par = G[v][i].second;
      continue;
    }
    go(to, v);
    tot += A[to];
    child ++;
  }
  B[v] = tot;

  for(int i = 0; i < G[v].size(); ++ i)
  {
    if(G[v][i].first == p)
      continue;
    for(int j = i + 1; j < G[v].size(); ++ j)
    {
      if(G[v][j].first == p)
        continue;
      B[v] = max(B[v], tot + B[G[v][i].first] + B[G[v][j].first] - A[G[v][i].first] - A[G[v][j].first] + G[v][i].second + G[v][j].second);
    }
  }
  A[v] = B[v];
  for(int i = 0; i < G[v].size(); ++ i)
  {
    int to = G[v][i].first;
    if(to == p)
      continue;
    A[v] = max(A[v], tot - A[to] + B[to] + par + G[v][i].second);
  }
}

int main()
{
  scanf("%d", &n);
  for(int i = 1; i < n; ++ i)
  {
    int x, y, val;
    scanf("%d %d %d", &x, &y, &val);
    G[x].push_back({y, val});
    G[y].push_back({x, val});
  }
  go(1);
  cout << A[1] << 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

5
1 2 10
1 3 40
1 4 15
1 5 20
*/

Compilation message (stderr)

beads.cpp: In function 'void go(int, int)':
beads.cpp:18:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < G[v].size(); ++ i)
                  ~~^~~~~~~~~~~~~
beads.cpp:32:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < G[v].size(); ++ i)
                  ~~^~~~~~~~~~~~~
beads.cpp:36:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int j = i + 1; j < G[v].size(); ++ j)
                        ~~^~~~~~~~~~~~~
beads.cpp:44:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < G[v].size(); ++ i)
                  ~~^~~~~~~~~~~~~
beads.cpp:17:6: warning: unused variable 'mx1' [-Wunused-variable]
   ll mx1 = -2e9, mx2 = -2e9, child = 0, tot = 0, par = -2e9;
      ^~~
beads.cpp:17:18: warning: unused variable 'mx2' [-Wunused-variable]
   ll mx1 = -2e9, mx2 = -2e9, child = 0, tot = 0, par = -2e9;
                  ^~~
beads.cpp: In function 'int main()':
beads.cpp:55:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
beads.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d", &x, &y, &val);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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