#include <bits/stdc++.h>
using namespace std;
constexpr int maxn = 2e5+10, inf = 0x3f3f3f3f; // subtask mudar
vector<pair<int,int>> g[maxn];
int dp[maxn][2]; // posso retornar com o pai livre ou sem o pai livre
void dfs(int u, int p, int peso_pai) {
for(auto [v, w] : g[u]) if(v != p) {
dfs(v, u, w);
dp[u][1] = max(dp[u][1], dp[v][0] + w + peso_pai - max(dp[v][0], dp[v][1]));
dp[u][0] += max(dp[v][0], dp[v][1]);
}
dp[u][1] += dp[u][0];
}
int ans;
void reroot(int u, int p) {
int sv0 = dp[u][0], sv1 = dp[u][1]; // dou roolback no final
int sz = (int)(g[u].size());
// vector<array<int,2>> pref(sz+1), suf(sz+1);
vector<array<int,2>> pref(sz+1, array<int,2>({0, -inf})), suf(sz+1, array<int,2>({0, -inf}));
for(int i = 0; i < sz; i++) {
auto [v, w] = g[u][i];
pref[i][1] = max(i ? pref[i-1][1] : -inf, dp[v][0] + w - max(dp[v][0], dp[v][1])); // tem que adicionar o peso_pai aqui
pref[i][0] = (i ? pref[i-1][0] : 0) + max(dp[v][0], dp[v][1]);
}
for(int i = sz-1; i >= 0; i--) {
auto [v, w] = g[u][i];
suf[i][1] = max(suf[i+1][1], dp[v][0] + w - max(dp[v][0], dp[v][1])); // tem que adicionar o peso_pai aqui
suf[i][0] = suf[i+1][0] + max(dp[v][0], dp[v][1]);
}
ans = max(ans, suf[0][0]);
// printf("%d %d %d\n", u, pref[sz-1][0], suf[0][0]);
for(int i = 0; i < sz; i++) {
if(g[u][i].first == p) continue;
dp[u][0] = (i ? pref[i-1][0] : 0) + suf[i+1][0];
dp[u][1] = dp[u][0] + max((i ? pref[i-1][1] : -inf), suf[i+1][1]) + (sz > 1 ? g[u][i].second : 0);
reroot(g[u][i].first, u);
}
dp[u][0] = sv0, dp[u][1] = sv1;
}
int main() {
int n; scanf("%d", &n);
for(int i = 1, a, b, w; i < n; i++)
scanf("%d %d %d", &a, &b, &w), g[a].push_back({b, w}), g[b].push_back({a, w});
int st;
for(int i = 1; i <= n; i++)
if(g[i].size() == 1) st = i; // acho qualquer folha
dfs(st, 0, 0);
reroot(st, 0);
printf("%d\n", ans);
}
Compilation message
beads.cpp: In function 'int main()':
beads.cpp:58:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
58 | int n; scanf("%d", &n);
| ~~~~~^~~~~~~~~~
beads.cpp:60:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
60 | scanf("%d %d %d", &a, &b, &w), g[a].push_back({b, w}), g[b].push_back({a, w});
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:65:8: warning: 'st' may be used uninitialized in this function [-Wmaybe-uninitialized]
65 | reroot(st, 0);
| ~~~~~~^~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
3 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
4 ms |
4948 KB |
Output is correct |
5 |
Correct |
3 ms |
4948 KB |
Output is correct |
6 |
Correct |
3 ms |
4948 KB |
Output is correct |
7 |
Correct |
3 ms |
4948 KB |
Output is correct |
8 |
Correct |
3 ms |
4948 KB |
Output is correct |
9 |
Correct |
4 ms |
4948 KB |
Output is correct |
10 |
Correct |
3 ms |
4948 KB |
Output is correct |
11 |
Correct |
3 ms |
4948 KB |
Output is correct |
12 |
Correct |
3 ms |
4948 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
3 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
4 ms |
4948 KB |
Output is correct |
5 |
Correct |
3 ms |
4948 KB |
Output is correct |
6 |
Correct |
3 ms |
4948 KB |
Output is correct |
7 |
Correct |
3 ms |
4948 KB |
Output is correct |
8 |
Correct |
3 ms |
4948 KB |
Output is correct |
9 |
Correct |
4 ms |
4948 KB |
Output is correct |
10 |
Correct |
3 ms |
4948 KB |
Output is correct |
11 |
Correct |
3 ms |
4948 KB |
Output is correct |
12 |
Correct |
3 ms |
4948 KB |
Output is correct |
13 |
Correct |
3 ms |
4948 KB |
Output is correct |
14 |
Correct |
3 ms |
5076 KB |
Output is correct |
15 |
Correct |
3 ms |
4948 KB |
Output is correct |
16 |
Correct |
3 ms |
5000 KB |
Output is correct |
17 |
Correct |
3 ms |
4948 KB |
Output is correct |
18 |
Correct |
4 ms |
5004 KB |
Output is correct |
19 |
Correct |
3 ms |
4948 KB |
Output is correct |
20 |
Correct |
3 ms |
5004 KB |
Output is correct |
21 |
Correct |
3 ms |
4948 KB |
Output is correct |
22 |
Correct |
3 ms |
4948 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
3 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
4 ms |
4948 KB |
Output is correct |
5 |
Correct |
3 ms |
4948 KB |
Output is correct |
6 |
Correct |
3 ms |
4948 KB |
Output is correct |
7 |
Correct |
3 ms |
4948 KB |
Output is correct |
8 |
Correct |
3 ms |
4948 KB |
Output is correct |
9 |
Correct |
4 ms |
4948 KB |
Output is correct |
10 |
Correct |
3 ms |
4948 KB |
Output is correct |
11 |
Correct |
3 ms |
4948 KB |
Output is correct |
12 |
Correct |
3 ms |
4948 KB |
Output is correct |
13 |
Correct |
3 ms |
4948 KB |
Output is correct |
14 |
Correct |
3 ms |
5076 KB |
Output is correct |
15 |
Correct |
3 ms |
4948 KB |
Output is correct |
16 |
Correct |
3 ms |
5000 KB |
Output is correct |
17 |
Correct |
3 ms |
4948 KB |
Output is correct |
18 |
Correct |
4 ms |
5004 KB |
Output is correct |
19 |
Correct |
3 ms |
4948 KB |
Output is correct |
20 |
Correct |
3 ms |
5004 KB |
Output is correct |
21 |
Correct |
3 ms |
4948 KB |
Output is correct |
22 |
Correct |
3 ms |
4948 KB |
Output is correct |
23 |
Correct |
6 ms |
5196 KB |
Output is correct |
24 |
Correct |
5 ms |
5204 KB |
Output is correct |
25 |
Correct |
6 ms |
5216 KB |
Output is correct |
26 |
Correct |
8 ms |
5528 KB |
Output is correct |
27 |
Correct |
8 ms |
5524 KB |
Output is correct |
28 |
Correct |
8 ms |
5788 KB |
Output is correct |
29 |
Correct |
8 ms |
5776 KB |
Output is correct |
30 |
Correct |
8 ms |
5716 KB |
Output is correct |
31 |
Correct |
9 ms |
6424 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
3 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
4 ms |
4948 KB |
Output is correct |
5 |
Correct |
3 ms |
4948 KB |
Output is correct |
6 |
Correct |
3 ms |
4948 KB |
Output is correct |
7 |
Correct |
3 ms |
4948 KB |
Output is correct |
8 |
Correct |
3 ms |
4948 KB |
Output is correct |
9 |
Correct |
4 ms |
4948 KB |
Output is correct |
10 |
Correct |
3 ms |
4948 KB |
Output is correct |
11 |
Correct |
3 ms |
4948 KB |
Output is correct |
12 |
Correct |
3 ms |
4948 KB |
Output is correct |
13 |
Correct |
3 ms |
4948 KB |
Output is correct |
14 |
Correct |
3 ms |
5076 KB |
Output is correct |
15 |
Correct |
3 ms |
4948 KB |
Output is correct |
16 |
Correct |
3 ms |
5000 KB |
Output is correct |
17 |
Correct |
3 ms |
4948 KB |
Output is correct |
18 |
Correct |
4 ms |
5004 KB |
Output is correct |
19 |
Correct |
3 ms |
4948 KB |
Output is correct |
20 |
Correct |
3 ms |
5004 KB |
Output is correct |
21 |
Correct |
3 ms |
4948 KB |
Output is correct |
22 |
Correct |
3 ms |
4948 KB |
Output is correct |
23 |
Correct |
6 ms |
5196 KB |
Output is correct |
24 |
Correct |
5 ms |
5204 KB |
Output is correct |
25 |
Correct |
6 ms |
5216 KB |
Output is correct |
26 |
Correct |
8 ms |
5528 KB |
Output is correct |
27 |
Correct |
8 ms |
5524 KB |
Output is correct |
28 |
Correct |
8 ms |
5788 KB |
Output is correct |
29 |
Correct |
8 ms |
5776 KB |
Output is correct |
30 |
Correct |
8 ms |
5716 KB |
Output is correct |
31 |
Correct |
9 ms |
6424 KB |
Output is correct |
32 |
Correct |
46 ms |
7564 KB |
Output is correct |
33 |
Correct |
36 ms |
7592 KB |
Output is correct |
34 |
Correct |
30 ms |
7568 KB |
Output is correct |
35 |
Correct |
185 ms |
14348 KB |
Output is correct |
36 |
Correct |
207 ms |
14436 KB |
Output is correct |
37 |
Correct |
225 ms |
14412 KB |
Output is correct |
38 |
Correct |
157 ms |
17584 KB |
Output is correct |
39 |
Correct |
124 ms |
17312 KB |
Output is correct |
40 |
Correct |
150 ms |
17420 KB |
Output is correct |
41 |
Correct |
196 ms |
24676 KB |
Output is correct |