#include "bits/stdc++.h"
using namespace std;
#define for_(i, s, e) for (int i = s; i < (int) e; i++)
#define for__(i, s, e) for (ll i = s; i < e; i++)
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
//#define endl '\n'
const int MXN = 2e5;
vector<array<int, 2>> dp;
vector<vector<array<int, 2>>> adj;
int n, ans = 0;
void dfs(int p, int parent, int pe=0) {
dp[p] = {0, 0};
int v = 0;
for (auto i: adj[p]) if (i[0] != parent) {
dfs(i[0], p, i[1]);
v = max(v, -dp[i[0]][0] + dp[i[0]][1] + i[1] + pe);
dp[p][1] += dp[i[0]][0];
}
dp[p][0] = dp[p][1] + (p == parent ? 0 : v);
}
void reroot(int p, int parent) {
array<int, 2> opt = {-1, -1}, pre = dp[p];
if (parent != p) dp[p][1] += dp[parent][0];
for (auto i: adj[p]) {
int temp = -dp[i[0]][0] + dp[i[0]][1] + i[1];
if (temp >= opt[0]) {
swap(opt[0], opt[1]);
opt[0] = temp;
} else if (temp > opt[1]) opt[1] = temp;
}
ans = max(ans, dp[p][1]);
for (auto i: adj[p]) if (i[0] != parent) {
dp[p][1] -= dp[i[0]][0];
dp[p][0] = dp[p][1];
int temp = -dp[i[0]][0] + dp[i[0]][1] + i[1];
if (temp == opt[0]) dp[p][0] += (opt[1] != -1 ? opt[1]+i[1] : 0);
else dp[p][0] += (opt[0] != -1 ? opt[0]+i[1] : 0);
reroot(i[0], p);
dp[p][1] += dp[i[0]][0];
}
dp[p] = pre;
}
int main() {
#ifdef mlocal
freopen("test.in", "r", stdin);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
dp.resize(n); adj.resize(n);
for_(i, 0, n-1) {
int a, b, w; cin >> a >> b >> w;
a -= 1; b -= 1;
adj[a].push_back({b, w}); adj[b].push_back({a, w});
}
dfs(0, 0, 0);
reroot(0, 0);
cout << ans << endl;
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
364 KB |
Output is correct |
| 3 |
Correct |
1 ms |
364 KB |
Output is correct |
| 4 |
Correct |
0 ms |
364 KB |
Output is correct |
| 5 |
Correct |
0 ms |
364 KB |
Output is correct |
| 6 |
Correct |
1 ms |
364 KB |
Output is correct |
| 7 |
Correct |
0 ms |
364 KB |
Output is correct |
| 8 |
Correct |
1 ms |
364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
364 KB |
Output is correct |
| 10 |
Correct |
1 ms |
364 KB |
Output is correct |
| 11 |
Correct |
1 ms |
364 KB |
Output is correct |
| 12 |
Correct |
0 ms |
364 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
364 KB |
Output is correct |
| 3 |
Correct |
1 ms |
364 KB |
Output is correct |
| 4 |
Correct |
0 ms |
364 KB |
Output is correct |
| 5 |
Correct |
0 ms |
364 KB |
Output is correct |
| 6 |
Correct |
1 ms |
364 KB |
Output is correct |
| 7 |
Correct |
0 ms |
364 KB |
Output is correct |
| 8 |
Correct |
1 ms |
364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
364 KB |
Output is correct |
| 10 |
Correct |
1 ms |
364 KB |
Output is correct |
| 11 |
Correct |
1 ms |
364 KB |
Output is correct |
| 12 |
Correct |
0 ms |
364 KB |
Output is correct |
| 13 |
Correct |
1 ms |
364 KB |
Output is correct |
| 14 |
Correct |
1 ms |
364 KB |
Output is correct |
| 15 |
Correct |
1 ms |
364 KB |
Output is correct |
| 16 |
Correct |
1 ms |
364 KB |
Output is correct |
| 17 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 18 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
364 KB |
Output is correct |
| 3 |
Correct |
1 ms |
364 KB |
Output is correct |
| 4 |
Correct |
0 ms |
364 KB |
Output is correct |
| 5 |
Correct |
0 ms |
364 KB |
Output is correct |
| 6 |
Correct |
1 ms |
364 KB |
Output is correct |
| 7 |
Correct |
0 ms |
364 KB |
Output is correct |
| 8 |
Correct |
1 ms |
364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
364 KB |
Output is correct |
| 10 |
Correct |
1 ms |
364 KB |
Output is correct |
| 11 |
Correct |
1 ms |
364 KB |
Output is correct |
| 12 |
Correct |
0 ms |
364 KB |
Output is correct |
| 13 |
Correct |
1 ms |
364 KB |
Output is correct |
| 14 |
Correct |
1 ms |
364 KB |
Output is correct |
| 15 |
Correct |
1 ms |
364 KB |
Output is correct |
| 16 |
Correct |
1 ms |
364 KB |
Output is correct |
| 17 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 18 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
312 KB |
Output is correct |
| 2 |
Correct |
1 ms |
364 KB |
Output is correct |
| 3 |
Correct |
1 ms |
364 KB |
Output is correct |
| 4 |
Correct |
0 ms |
364 KB |
Output is correct |
| 5 |
Correct |
0 ms |
364 KB |
Output is correct |
| 6 |
Correct |
1 ms |
364 KB |
Output is correct |
| 7 |
Correct |
0 ms |
364 KB |
Output is correct |
| 8 |
Correct |
1 ms |
364 KB |
Output is correct |
| 9 |
Correct |
1 ms |
364 KB |
Output is correct |
| 10 |
Correct |
1 ms |
364 KB |
Output is correct |
| 11 |
Correct |
1 ms |
364 KB |
Output is correct |
| 12 |
Correct |
0 ms |
364 KB |
Output is correct |
| 13 |
Correct |
1 ms |
364 KB |
Output is correct |
| 14 |
Correct |
1 ms |
364 KB |
Output is correct |
| 15 |
Correct |
1 ms |
364 KB |
Output is correct |
| 16 |
Correct |
1 ms |
364 KB |
Output is correct |
| 17 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 18 |
Halted |
0 ms |
0 KB |
- |
