Submission #48296

#	Time	Username	Problem	Language	Result	Execution time	Memory
48296		octopuses	Beads and wires (APIO14_beads)	C++17	0 / 100	7 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;
int A[N], B[N];

void go(int v, int p = 0)
{
  int mx1 = -100, mx2 = -100, 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];
    int now = B[to] - A[to] + G[v][i].second;
    if(now > mx1)
    {
      mx2 = mx1;
      mx1 = now;
    }
    else
      if(now > mx2)
        mx2 = now;
    child ++;
  }
  A[v] = B[v] = tot;
  if(child > 1)
    B[v] = max(tot + mx1 + mx2, B[v]);
  A[v] = max(B[v], A[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);
  printf("%d\n", A[1]);
}

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:43:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < G[v].size(); ++ i)
                  ~~^~~~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:54:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
beads.cpp:58:10: 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