#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define ll long long
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define pill pair<ll, ll>
using namespace std;
const ll N = 1e4 + 10;
const ll big = 1e9;
ll n;
vector<pair<int,int>> g[N];
int dp[N][2];
int dfs(int v, int p, int z) {
dp[v][0] = dp[v][1] = 0;
int dp2[3];
dp2[0] = 0, dp2[1] = -big, dp2[2] = -big;
for(auto u : g[v]) {
if(u.f != p) {
dfs(u.f, v, u.s);
int z = max(dp[u.f][0], dp[u.f][1]);
dp2[2] = max(dp2[2] + z, dp2[1] + dp[u.f][0] + u.s);
dp2[1] = max(dp2[1] + z, dp2[0] + dp[u.f][0] + u.s);
dp2[0] = dp2[0] + z;
}
}
dp[v][0] = dp2[0];
dp[v][1] = dp2[1] + z;
ans = max(ans, dp2[2]);
}
int main() {
speed;
cin >> n;
for(int i = 1, a, b, c; i < n; i++)
cin >> a >> b >> c, g[a].pb(mp(b, c)), g[b].pb(mp(a, c));
int ans = 0;
for(int i = 1; i <= n; i++)
dfs(i, 0, 0);
cout << ans;
}
/*
10
5 6 9
2 3 5
1 10 8
4 5 9
2 7 8
5 7 10
6 9 4
2 8 9
1 7 5
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
*/
Compilation message
beads.cpp: In function 'int dfs(int, int, int)':
beads.cpp:34:2: error: 'ans' was not declared in this scope; did you mean 'abs'?
34 | ans = max(ans, dp2[2]);
| ^~~
| abs
beads.cpp:35:1: warning: no return statement in function returning non-void [-Wreturn-type]
35 | }
| ^
