#include <bits/stdc++.h>
using namespace std;
constexpr int maxn = 2e5+10, inf = 0x3f3f3f3f;
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, 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]);
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});
dfs(1, 0, 0);
reroot(1, 0);
printf("%d\n", ans);
}
Compilation message
beads.cpp: In function 'int main()':
beads.cpp:55:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
55 | int n; scanf("%d", &n);
| ~~~~~^~~~~~~~~~
beads.cpp:57:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
57 | scanf("%d %d %d", &a, &b, &w), g[a].push_back({b, w}), g[b].push_back({a, w});
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 6 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 7 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 8 |
Correct |
4 ms |
4944 KB |
Output is correct |
| 9 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 10 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 11 |
Correct |
4 ms |
4948 KB |
Output is correct |
| 12 |
Correct |
3 ms |
4948 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 6 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 7 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 8 |
Correct |
4 ms |
4944 KB |
Output is correct |
| 9 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 10 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 11 |
Correct |
4 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 |
4948 KB |
Output is correct |
| 15 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 16 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 17 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 18 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 19 |
Correct |
3 ms |
5076 KB |
Output is correct |
| 20 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 21 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 22 |
Correct |
3 ms |
4948 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 6 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 7 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 8 |
Correct |
4 ms |
4944 KB |
Output is correct |
| 9 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 10 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 11 |
Correct |
4 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 |
4948 KB |
Output is correct |
| 15 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 16 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 17 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 18 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 19 |
Correct |
3 ms |
5076 KB |
Output is correct |
| 20 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 21 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 22 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 23 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 24 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 25 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 26 |
Correct |
8 ms |
5332 KB |
Output is correct |
| 27 |
Correct |
8 ms |
5332 KB |
Output is correct |
| 28 |
Correct |
8 ms |
5588 KB |
Output is correct |
| 29 |
Correct |
8 ms |
5588 KB |
Output is correct |
| 30 |
Correct |
7 ms |
5460 KB |
Output is correct |
| 31 |
Correct |
8 ms |
6228 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 6 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 7 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 8 |
Correct |
4 ms |
4944 KB |
Output is correct |
| 9 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 10 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 11 |
Correct |
4 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 |
4948 KB |
Output is correct |
| 15 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 16 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 17 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 18 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 19 |
Correct |
3 ms |
5076 KB |
Output is correct |
| 20 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 21 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 22 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 23 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 24 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 25 |
Correct |
5 ms |
5204 KB |
Output is correct |
| 26 |
Correct |
8 ms |
5332 KB |
Output is correct |
| 27 |
Correct |
8 ms |
5332 KB |
Output is correct |
| 28 |
Correct |
8 ms |
5588 KB |
Output is correct |
| 29 |
Correct |
8 ms |
5588 KB |
Output is correct |
| 30 |
Correct |
7 ms |
5460 KB |
Output is correct |
| 31 |
Correct |
8 ms |
6228 KB |
Output is correct |
| 32 |
Correct |
41 ms |
7140 KB |
Output is correct |
| 33 |
Correct |
37 ms |
7164 KB |
Output is correct |
| 34 |
Correct |
29 ms |
7248 KB |
Output is correct |
| 35 |
Correct |
213 ms |
14032 KB |
Output is correct |
| 36 |
Correct |
223 ms |
14156 KB |
Output is correct |
| 37 |
Correct |
201 ms |
14032 KB |
Output is correct |
| 38 |
Correct |
150 ms |
17076 KB |
Output is correct |
| 39 |
Correct |
142 ms |
17484 KB |
Output is correct |
| 40 |
Correct |
172 ms |
17080 KB |
Output is correct |
| 41 |
Correct |
230 ms |
24208 KB |
Output is correct |
