// C
#ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#endif
// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#endif
#define va first
#define vb second
#define lb lower_bound
#define ub upper_bound
#define bs binary_search
#define pp push_back
#define ep emplace_back
#define all(v) (v).begin(),(v).end()
#define szz(v) ((int)(v).size())
#define bi_pc __builtin_popcount
#define bi_pcll __builtin_popcountll
#define bi_tz __builtin_ctz
#define bi_tzll __builtin_ctzll
#define fio ios_base::sync_with_stdio(0);cin.tie(0);
#ifdef TAMREF
#define debug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...) 42
#endif
using namespace std;
template<typename ...Args>
void logger(string vars, Args&&... values) {
cerr << vars << " = ";
string delim = "";
(..., (cerr << delim << values, delim = ", "));
cerr << '\n';
}
#ifdef TAMREF
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
#else
#define deb(...) 42
#endif
using ll = long long; using lf = long double;
using pii = pair<int,int>; using ppi = pair<int,pii>;
using pll = pair<ll,ll>; using pff = pair<lf,lf>;
using ti = tuple<int,int,int>;
using base = complex<double>;
const lf PI = 3.14159265358979323846264338L;
template <typename T>
inline T umax(T& u, T v){return u = max(u, v);}
template <typename T>
inline T umin(T& u, T v){return u = min(u, v);}
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
vector<pll> G[200005];
ll dp[200005][2];
int vis[200005];
int n;
ll ans;
void dfs(int x) {
vis[x] = 1;
vector<ll> P(2);
P[0] = LLONG_MIN;
vector<pll> subdp[2];
subdp[0].clear();
subdp[1].clear();
for(auto &[u, w] : G[x]) {
if(vis[u]) continue;
dfs(u);
for(int b = 0; b < 2; b++) {
for(int c = 0; c < 2; c++) {
ll cand = dp[u][b] + P[c];
if(b || dp[u][b]) cand += w;
umax(dp[x][b ^ c], cand);
}
}
if(dp[u][0]) {
umax(P[1], dp[u][0] + w);
subdp[0].ep(dp[u][0] + w, u);
}
umax(P[0], dp[u][1] + w);
subdp[1].ep(dp[u][1] + w, u);
}
debug("dp[%d][%d] = %lld, dp[%d][%d] = %lld\n", x, 0, dp[x][0], x, 1, dp[x][1]);
if(szz(G[x]) >= 3) {
sort(all(subdp[0]), greater<pll>());
sort(all(subdp[1]), greater<pll>());
// 0 0 0
if(szz(subdp[0]) >= 3) {
umax(ans, subdp[0][0].va + subdp[0][1].va + subdp[0][2].va);
}
// 1 1 0
if(szz(subdp[1]) >= 2) {
int i1 = subdp[1][0].vb, i2 = subdp[1][1].vb;
auto it = find_if(all(subdp[0]), [&](pll u) {
return u.vb != i1 && u.vb != i2;
});
if(it != subdp[0].end()) umax(ans, subdp[1][0].va + subdp[1][0].va + it -> va);
}
// 0 1 1
if(szz(subdp[0])) {
ll cc = subdp[0][0].va + subdp[1][0].va;
int i1 = subdp[0][0].vb, i2 = subdp[1][0].vb;
if(i1 == i2) {
i2 = subdp[1][1].vb;
cc += subdp[1][1].va - subdp[1][0].va;
}
auto it = find_if(all(subdp[1]), [&](pll u) {
return u.vb != i1 && u.vb != i2;
});
umax(ans, cc + it -> va);
}
if(szz(subdp[0])) {
// 1 0 1
ll cc = subdp[1][0].va + subdp[0][0].va;
int i1 = subdp[1][0].vb, i2 = subdp[0][0].vb;
if(i1 == i2 && szz(subdp[0]) >= 2) {
i2 = subdp[0][1].vb;
cc += subdp[0][1].va - subdp[0][0].va;
}
if(i1 != i2) {
auto it = find_if(all(subdp[1]), [&](pll u) {
return u.vb != i1 && u.vb != i2;
});
umax(ans, cc + it -> va);
}
}
}
}
int main(){
fio;
cin >> n;
for(int i = 1, a, b, c; i < n; i++) {
cin >> a >> b >> c;
G[a].ep(b, c);
G[b].ep(a, c);
}
dfs(1);
for(int i = 1; i <= n; i++) umax(ans, dp[i][1]);
cout << ans << '\n';
}
Compilation message
beads.cpp: In function 'void dfs(int)':
beads.cpp:104:20: warning: statement has no effect [-Wunused-value]
104 | #define debug(...) 42
| ^~
beads.cpp:163:5: note: in expansion of macro 'debug'
163 | debug("dp[%d][%d] = %lld, dp[%d][%d] = %lld\n", x, 0, dp[x][0], x, 1, dp[x][1]);
| ^~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
