#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back
using namespace std;
typedef pair<int, int> pii;
const int N = 2e5 + 5;
vector<pii> G[N];
int dp[N][4], W[N], p[N];
void dfs(int v, int par = -1){
for(auto [i, w] : G[v]){
if(i == par) continue;
W[i] = w;
dfs(i, v);
}
// Case 0: do nothing
int a0 = 0, a1 = 0;
vector<int> tune1;
for(auto [i, w] : G[v]){
if(i != par) a0 += max(dp[i][1], dp[i][2]), a1 += max(dp[i][1], dp[i][2]), tune1.pb(dp[i][3] - max(dp[i][1], dp[i][2]));
}
sort(tune1.begin(), tune1.end(), greater<>()); if(tune1.size()) a1 += tune1[0];
dp[v][0] = a0, dp[v][1] = a1;
// Case 1: p[v]-v-son[v]
vector<pii> co2, co3;
for(auto [i, w] : G[v]){
if(i != par) co2.pb({w + dp[i][0] - max(dp[i][1], dp[i][2]), i}), co3.pb({w + dp[i][1] - max(dp[i][1], dp[i][2]), i});
}
sort(co2.begin(), co2.end(), greater<>());
sort(co3.begin(), co3.end(), greater<>());
// for(auto i : co2) cout << i << ' '; cout << endl;
// for(auto i : co3) cout << i << ' '; cout << endl;
if(par != -1){
if(co2.size()) dp[v][2] = max(dp[v][2], a0 + co2[0].fi + W[v]);
if(co3.size()) dp[v][3] = max(dp[v][3], a0 + co3[0].fi + W[v]);
}
// Case 2: son1[v]-v-son2[v]
if(co2.size() >= 2) dp[v][1] = max(dp[v][1], a0 + (co2[0].se == co3[0].se ? max(co2[0].fi + co3[1].fi, co2[1].fi + co3[0].fi) : co2[0].fi + co3[0].fi));
dp[v][2] = max(dp[v][0], dp[v][2]);
dp[v][1] = max(dp[v][0], dp[v][1]);
dp[v][3] = max(dp[v][1], dp[v][3]);
dp[v][3] = max(dp[v][2], dp[v][3]);
}
int32_t main(){
int n;
cin >> n;
for(int i = 0; i < n - 1; i++){
int u, v, we;
cin >> u >> v >> we;
G[u].pb({v, we});
G[v].pb({u, we});
}
dfs(1);
// for(int i = 1; i <= n; i++){
// cout << i << ": " << dp[i][0] << ' ' << dp[i][1] << ' ' << dp[i][2] << ' ' << dp[i][3] << endl;
// }
int ans = 0; for(int j = 0; j < 4; j++) ans = max(ans, dp[1][j]);
cout << ans << endl;
}
Compilation message
beads.cpp: In function 'void dfs(long long int, long long int)':
beads.cpp:14:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
14 | for(auto [i, w] : G[v]){
| ^
beads.cpp:22:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
22 | for(auto [i, w] : G[v]){
| ^
beads.cpp:29:11: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
29 | for(auto [i, w] : G[v]){
| ^
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
4 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
3 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 |
4956 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 |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
4 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
3 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 |
4956 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 |
Incorrect |
3 ms |
5004 KB |
Output isn't correct |
14 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
4 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
3 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 |
4956 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 |
Incorrect |
3 ms |
5004 KB |
Output isn't correct |
14 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
4948 KB |
Output is correct |
2 |
Correct |
4 ms |
4948 KB |
Output is correct |
3 |
Correct |
3 ms |
4948 KB |
Output is correct |
4 |
Correct |
3 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 |
4956 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 |
Incorrect |
3 ms |
5004 KB |
Output isn't correct |
14 |
Halted |
0 ms |
0 KB |
- |