#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
int const maxn = 10001;
struct Edge {
int u, w;
};
vector<Edge> v[maxn];
int n;
int dp[2][maxn];
inline int invalid(int x) {
return v[x].size() == 1;
}
int solve(int x, int p = -1, int t = 0) {
if (dp[x][t] >= 0) return dp[x][t];
int d = 0;
if (t == 0) {
for (Edge const& e : v[x]) {
if (e.u == p) continue;
if (!invalid(e.u)) {
d += max(solve(e.u, x, 1) + e.w, solve(e.u, x, 0));
}
}
}
else {
int sum = solve(x, p, 0);
for (Edge const& e : v[x]) {
if (e.u == p) continue;
if (!invalid(e.u))
d = max(d, sum - max(solve(e.u, x, 1) + e.w, solve(e.u, x, 0))
+ e.w + solve(e.u, x, 0));
else
d = max(d, sum + e.w);
}
}
return dp[x][t] = d;
}
vector<int> bfs_order(int ini) {
vector<int> vis(n+1);
queue<int> q {{ini}};
vis[ini] = 1;
vector<int> res;
while (!q.empty()) {
int x = q.front();
res.push_back(x);
q.pop();
for (Edge const& e : v[x]) {
if (vis[e.u]) continue;
vis[e.u] = 1;
q.push(e.u);
}
}
reverse(res.begin(), res.end());
return res;
}
inline int test(int ini) {
memset(dp, 0, sizeof(dp));
auto order = bfs_order(ini);
vector<int> vis(n+1);
for (int x : order) {
vis[x] = 1;
int d = 0;
for (Edge const& e : v[x]) {
if (!vis[e.u]) continue;
if (!invalid(e.u)) {
d += max(dp[1][e.u] + e.w, dp[0][e.u]);
}
}
dp[0][x] = d;
d = 0;
int sum = dp[0][x];
for (Edge const& e : v[x]) {
if (!vis[e.u]) continue;
if (!invalid(e.u))
d = max(d, sum - max(dp[1][e.u] + e.w, dp[0][e.u])
+ e.w + dp[0][e.u]);
else
d = max(d, sum + e.w);
}
dp[1][x] = d;
}
return dp[0][ini];
}
int main() {
ios::sync_with_stdio(false), cin.tie(nullptr);
cin >> n;
for (int i = 0; i < n-1; i++) {
int a, b, w;
cin >> a >> b >> w;
v[a].push_back({b, w});
v[b].push_back({a, w});
}
int ans = 0;
for (int i = 1; i <= n; i++)
if (v[i].size() == 1)
ans = max(ans, test(i));
cout << ans << "\n";
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
632 KB |
Output is correct |
2 |
Correct |
2 ms |
632 KB |
Output is correct |
3 |
Correct |
2 ms |
632 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
3 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
632 KB |
Output is correct |
9 |
Correct |
2 ms |
760 KB |
Output is correct |
10 |
Correct |
3 ms |
632 KB |
Output is correct |
11 |
Correct |
3 ms |
632 KB |
Output is correct |
12 |
Correct |
2 ms |
632 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
632 KB |
Output is correct |
2 |
Correct |
2 ms |
632 KB |
Output is correct |
3 |
Correct |
2 ms |
632 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
3 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
632 KB |
Output is correct |
9 |
Correct |
2 ms |
760 KB |
Output is correct |
10 |
Correct |
3 ms |
632 KB |
Output is correct |
11 |
Correct |
3 ms |
632 KB |
Output is correct |
12 |
Correct |
2 ms |
632 KB |
Output is correct |
13 |
Correct |
3 ms |
632 KB |
Output is correct |
14 |
Correct |
3 ms |
632 KB |
Output is correct |
15 |
Correct |
3 ms |
632 KB |
Output is correct |
16 |
Correct |
4 ms |
632 KB |
Output is correct |
17 |
Correct |
3 ms |
632 KB |
Output is correct |
18 |
Correct |
3 ms |
632 KB |
Output is correct |
19 |
Correct |
4 ms |
632 KB |
Output is correct |
20 |
Correct |
4 ms |
632 KB |
Output is correct |
21 |
Correct |
4 ms |
632 KB |
Output is correct |
22 |
Correct |
4 ms |
632 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
632 KB |
Output is correct |
2 |
Correct |
2 ms |
632 KB |
Output is correct |
3 |
Correct |
2 ms |
632 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
3 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
632 KB |
Output is correct |
9 |
Correct |
2 ms |
760 KB |
Output is correct |
10 |
Correct |
3 ms |
632 KB |
Output is correct |
11 |
Correct |
3 ms |
632 KB |
Output is correct |
12 |
Correct |
2 ms |
632 KB |
Output is correct |
13 |
Correct |
3 ms |
632 KB |
Output is correct |
14 |
Correct |
3 ms |
632 KB |
Output is correct |
15 |
Correct |
3 ms |
632 KB |
Output is correct |
16 |
Correct |
4 ms |
632 KB |
Output is correct |
17 |
Correct |
3 ms |
632 KB |
Output is correct |
18 |
Correct |
3 ms |
632 KB |
Output is correct |
19 |
Correct |
4 ms |
632 KB |
Output is correct |
20 |
Correct |
4 ms |
632 KB |
Output is correct |
21 |
Correct |
4 ms |
632 KB |
Output is correct |
22 |
Correct |
4 ms |
632 KB |
Output is correct |
23 |
Execution timed out |
1016 ms |
1020 KB |
Time limit exceeded |
24 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
632 KB |
Output is correct |
2 |
Correct |
2 ms |
632 KB |
Output is correct |
3 |
Correct |
2 ms |
632 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
3 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
632 KB |
Output is correct |
9 |
Correct |
2 ms |
760 KB |
Output is correct |
10 |
Correct |
3 ms |
632 KB |
Output is correct |
11 |
Correct |
3 ms |
632 KB |
Output is correct |
12 |
Correct |
2 ms |
632 KB |
Output is correct |
13 |
Correct |
3 ms |
632 KB |
Output is correct |
14 |
Correct |
3 ms |
632 KB |
Output is correct |
15 |
Correct |
3 ms |
632 KB |
Output is correct |
16 |
Correct |
4 ms |
632 KB |
Output is correct |
17 |
Correct |
3 ms |
632 KB |
Output is correct |
18 |
Correct |
3 ms |
632 KB |
Output is correct |
19 |
Correct |
4 ms |
632 KB |
Output is correct |
20 |
Correct |
4 ms |
632 KB |
Output is correct |
21 |
Correct |
4 ms |
632 KB |
Output is correct |
22 |
Correct |
4 ms |
632 KB |
Output is correct |
23 |
Execution timed out |
1016 ms |
1020 KB |
Time limit exceeded |
24 |
Halted |
0 ms |
0 KB |
- |