#include<bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define endl "\n"
using namespace std;
const int N = 2e5 + 10;
int f[N], g[N], h[N];
int _f[N], _g[N], _h[N];
int maxw[2][N];
vector<pair<int, int> > adj[N];
void dfs(int u, int p) {
maxw[0][u] = maxw[1][u] = -1e9;
for(auto &[v, w] : adj[u]) if (v != p) {
dfs(v, u);
h[v] = max(f[v], g[v] + w);
f[u] += h[v];
maxw[1][u] = max(maxw[1][u], w + f[v] - h[v]);
if (maxw[0][u] < maxw[1][u]) swap(maxw[0][u], maxw[1][u]);
}
g[u] = f[u] + maxw[0][u];
}
void _dfs(int u, int p, int w, int pre_cost) {
if (p) {
_f[u] = f[p] - h[u] + _h[p];
int cost = maxw[0][p];
if (w + f[u] - h[u] == cost) cost = maxw[1][p];
cost = max(cost, pre_cost);
_g[u] = _f[u] + cost;
_h[u] = max(_f[u], _g[u] + w);
int new_cost = w + _f[u] - _h[u];
pre_cost = new_cost;
}
for(auto &[v, next_w] : adj[u]) if (v != p) {
_dfs(v, u, next_w, pre_cost);
}
}
int32_t main() {
#define task ""
cin.tie(0) -> sync_with_stdio(0);
if (fopen("task.inp", "r")) {
freopen("task.inp", "r", stdin);
freopen("task.out", "w", stdout);
}
if (fopen(task".inp", "r")) {
freopen (task".inp", "r", stdin);
freopen (task".out", "w", stdout);
}
int n; cin >> n;
for(int i = 1; i < n; i++) {
int a, b, c; cin >> a >> b >> c;
adj[a].emplace_back(b, c);
adj[b].emplace_back(a, c);
}
dfs(1, 0);
_dfs(1, 0, 0, -1e9);
int ans = 0;
for(int i = 1; i <= n; i++) {
ans = max(ans, f[i] + _h[i]);
}
cout << ans;
}
Compilation message
beads.cpp: In function 'int32_t main()':
beads.cpp:51:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
51 | freopen("task.inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:52:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
52 | freopen("task.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:56:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
56 | freopen (task".inp", "r", stdin);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:57:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
57 | freopen (task".out", "w", stdout);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
8792 KB |
Output is correct |
2 |
Correct |
2 ms |
8796 KB |
Output is correct |
3 |
Correct |
2 ms |
8796 KB |
Output is correct |
4 |
Correct |
1 ms |
8796 KB |
Output is correct |
5 |
Correct |
2 ms |
8796 KB |
Output is correct |
6 |
Correct |
2 ms |
8796 KB |
Output is correct |
7 |
Correct |
1 ms |
8796 KB |
Output is correct |
8 |
Correct |
1 ms |
8792 KB |
Output is correct |
9 |
Correct |
2 ms |
8796 KB |
Output is correct |
10 |
Correct |
2 ms |
8796 KB |
Output is correct |
11 |
Correct |
1 ms |
8796 KB |
Output is correct |
12 |
Correct |
2 ms |
8796 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
8792 KB |
Output is correct |
2 |
Correct |
2 ms |
8796 KB |
Output is correct |
3 |
Correct |
2 ms |
8796 KB |
Output is correct |
4 |
Correct |
1 ms |
8796 KB |
Output is correct |
5 |
Correct |
2 ms |
8796 KB |
Output is correct |
6 |
Correct |
2 ms |
8796 KB |
Output is correct |
7 |
Correct |
1 ms |
8796 KB |
Output is correct |
8 |
Correct |
1 ms |
8792 KB |
Output is correct |
9 |
Correct |
2 ms |
8796 KB |
Output is correct |
10 |
Correct |
2 ms |
8796 KB |
Output is correct |
11 |
Correct |
1 ms |
8796 KB |
Output is correct |
12 |
Correct |
2 ms |
8796 KB |
Output is correct |
13 |
Correct |
2 ms |
8796 KB |
Output is correct |
14 |
Correct |
2 ms |
8796 KB |
Output is correct |
15 |
Correct |
2 ms |
8796 KB |
Output is correct |
16 |
Correct |
2 ms |
8796 KB |
Output is correct |
17 |
Correct |
2 ms |
8796 KB |
Output is correct |
18 |
Correct |
2 ms |
8796 KB |
Output is correct |
19 |
Correct |
2 ms |
8796 KB |
Output is correct |
20 |
Correct |
2 ms |
9048 KB |
Output is correct |
21 |
Correct |
2 ms |
8796 KB |
Output is correct |
22 |
Correct |
2 ms |
8796 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
8792 KB |
Output is correct |
2 |
Correct |
2 ms |
8796 KB |
Output is correct |
3 |
Correct |
2 ms |
8796 KB |
Output is correct |
4 |
Correct |
1 ms |
8796 KB |
Output is correct |
5 |
Correct |
2 ms |
8796 KB |
Output is correct |
6 |
Correct |
2 ms |
8796 KB |
Output is correct |
7 |
Correct |
1 ms |
8796 KB |
Output is correct |
8 |
Correct |
1 ms |
8792 KB |
Output is correct |
9 |
Correct |
2 ms |
8796 KB |
Output is correct |
10 |
Correct |
2 ms |
8796 KB |
Output is correct |
11 |
Correct |
1 ms |
8796 KB |
Output is correct |
12 |
Correct |
2 ms |
8796 KB |
Output is correct |
13 |
Correct |
2 ms |
8796 KB |
Output is correct |
14 |
Correct |
2 ms |
8796 KB |
Output is correct |
15 |
Correct |
2 ms |
8796 KB |
Output is correct |
16 |
Correct |
2 ms |
8796 KB |
Output is correct |
17 |
Correct |
2 ms |
8796 KB |
Output is correct |
18 |
Correct |
2 ms |
8796 KB |
Output is correct |
19 |
Correct |
2 ms |
8796 KB |
Output is correct |
20 |
Correct |
2 ms |
9048 KB |
Output is correct |
21 |
Correct |
2 ms |
8796 KB |
Output is correct |
22 |
Correct |
2 ms |
8796 KB |
Output is correct |
23 |
Correct |
4 ms |
9052 KB |
Output is correct |
24 |
Correct |
3 ms |
9048 KB |
Output is correct |
25 |
Correct |
4 ms |
9048 KB |
Output is correct |
26 |
Correct |
5 ms |
9308 KB |
Output is correct |
27 |
Correct |
4 ms |
9308 KB |
Output is correct |
28 |
Correct |
4 ms |
9308 KB |
Output is correct |
29 |
Correct |
4 ms |
9304 KB |
Output is correct |
30 |
Correct |
4 ms |
9308 KB |
Output is correct |
31 |
Correct |
5 ms |
9564 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
8792 KB |
Output is correct |
2 |
Correct |
2 ms |
8796 KB |
Output is correct |
3 |
Correct |
2 ms |
8796 KB |
Output is correct |
4 |
Correct |
1 ms |
8796 KB |
Output is correct |
5 |
Correct |
2 ms |
8796 KB |
Output is correct |
6 |
Correct |
2 ms |
8796 KB |
Output is correct |
7 |
Correct |
1 ms |
8796 KB |
Output is correct |
8 |
Correct |
1 ms |
8792 KB |
Output is correct |
9 |
Correct |
2 ms |
8796 KB |
Output is correct |
10 |
Correct |
2 ms |
8796 KB |
Output is correct |
11 |
Correct |
1 ms |
8796 KB |
Output is correct |
12 |
Correct |
2 ms |
8796 KB |
Output is correct |
13 |
Correct |
2 ms |
8796 KB |
Output is correct |
14 |
Correct |
2 ms |
8796 KB |
Output is correct |
15 |
Correct |
2 ms |
8796 KB |
Output is correct |
16 |
Correct |
2 ms |
8796 KB |
Output is correct |
17 |
Correct |
2 ms |
8796 KB |
Output is correct |
18 |
Correct |
2 ms |
8796 KB |
Output is correct |
19 |
Correct |
2 ms |
8796 KB |
Output is correct |
20 |
Correct |
2 ms |
9048 KB |
Output is correct |
21 |
Correct |
2 ms |
8796 KB |
Output is correct |
22 |
Correct |
2 ms |
8796 KB |
Output is correct |
23 |
Correct |
4 ms |
9052 KB |
Output is correct |
24 |
Correct |
3 ms |
9048 KB |
Output is correct |
25 |
Correct |
4 ms |
9048 KB |
Output is correct |
26 |
Correct |
5 ms |
9308 KB |
Output is correct |
27 |
Correct |
4 ms |
9308 KB |
Output is correct |
28 |
Correct |
4 ms |
9308 KB |
Output is correct |
29 |
Correct |
4 ms |
9304 KB |
Output is correct |
30 |
Correct |
4 ms |
9308 KB |
Output is correct |
31 |
Correct |
5 ms |
9564 KB |
Output is correct |
32 |
Correct |
18 ms |
11100 KB |
Output is correct |
33 |
Correct |
19 ms |
11100 KB |
Output is correct |
34 |
Correct |
19 ms |
11328 KB |
Output is correct |
35 |
Correct |
90 ms |
18816 KB |
Output is correct |
36 |
Correct |
104 ms |
22352 KB |
Output is correct |
37 |
Correct |
106 ms |
22612 KB |
Output is correct |
38 |
Correct |
74 ms |
22720 KB |
Output is correct |
39 |
Correct |
62 ms |
21908 KB |
Output is correct |
40 |
Correct |
76 ms |
22456 KB |
Output is correct |
41 |
Correct |
115 ms |
26096 KB |
Output is correct |