| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 586336 | xynex | Race (IOI11_race) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
/**
* Author: Tenjin
* Created: 28.06.2022 14:48
* Why am I so stupid? :c
* Slishkom slab
**/
#include <bits/stdc++.h>
// #pragma GCC optimize("inline")
// #pragma GCC optimize("-fgcse,-fgcse-lm")
// #pragma GCC optimize("-ftree-pre,-ftree-vrp")
// #pragma GCC optimize("-ffast-math")
// #pragma GCC optimize("-fipa-sra")
// #pragma GCC optimize("-fpeephole2")
// #pragma GCC optimize("-fsched-spec")
// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define ll long long
#define dl double long
#define ull unsigned long long
#define pr pair
#define vt vector
#define ff first
#define ss second
#define mp make_pair
#define sz(a) (int)a.size()
#define pb push_back
#define pf push_front
#define popB pop_back
#define popF pop_front
#define bit_count __builtin_popcount
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sp(x) fixed << setprecision(x)
template<typename T> T get_rand(T l, T r) {
random_device rd;
mt19937 gen(rd());
return uniform_int_distribution<T>(l, r)(gen);
}
template<typename T> T lcm(T a, T b) { return a * (b / __gcd(a, b)); }
template<class A> void read(vt<A>& v);
template<class A, size_t S> void read(array<A, S>& a);
template<class T> void read(T& x) { cin >> x; }
void read(double& d) { string t; read(t); d = stod(t); }
void read(long double& d) { string t; read(t); d = stold(t); }
template<class H, class... T> void read(H& h, T&... t) { read(h); read(t...); }
template<class A> void read(vt<A>& x) { for (auto& a : x) read(a); }
template<class A, size_t S> void read(array<A, S>& x) { for (auto& a : x) read(a); }
string to_string(char c) { return string(1, c); }
string to_string(bool b) { return b ? "true" : "false"; }
string to_string(const char* s) { return string(s); }
string to_string(string s) { return s; }
string to_string(vt<bool> v) { string res; for (int i = 0; i < sz(v); ++i) res += char('0' + v[i]); return res; }
template<size_t S> string to_string(bitset<S> b) { string res; for (int i = 0; i < S; ++i) res += char('0' + b[i]); return res; }
template<class T> string to_string(T v) { bool f = 1; string res; for (auto x : v) { if (!f) res += ' '; f = 0; res += to_string(x); } return res; }
template<class A> void write(A x) { cout << to_string(x); }
template<class H, class... T> void write(const H& h, const T&... t) { write(h); write(t...); }
void print() { write("\n"); }
template<class H, class... T> void print(const H& h, const T&... t) { write(h); if (sizeof...(t)) write(' '); print(t...); }
void freop(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
const int MOD = 1e9 + 7;
const int N = 3e6 + 5;
const ll INF = 9e18;
const int M = 3e3 + 5;
const dl pi = acos(-1);
const dl eps = 1e-12;
const int sq = 700;
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};
/* ll vs int*/
vt<pr<int, int> > g[N];
int n, k, G[N][2], l[N];
ll ans;
set<pr<int, ll> > d[N];
void dfs(int v, int p = -1, int dist = 0, int dep = 0) {
d[v].insert({dist, dep});
for(auto to : g[v]) {
if(to.ff == p) continue;
dfs(to.ff, v, dist + to.ss, dep + 1);
if(sz(d[v]) < sz(d[to.ff])) swap(d[v], d[to.ff]);
for(auto ind : d[to.ff]) {
int need = k - ind.ff + dist * 2;
auto whr = d[v].lower_bound({need, -1});
if(whr == d[v].end()) continue;
auto cur = *whr;
if(cur.ff != need) continue;
ans = min(ans, (ll)cur.ss + (ll)ind.ss - (ll)dep * 2);
}
for(auto ind : d[to.ff]) d[v].insert(ind);
}
}
int best_path(int n, int k, int G[][2], int l[]) {
for(int i = 1; i < n; ++i) {
g[G[i][0]].pb({G[i][1], l[i]});
g[G[i][1]].pb({G[i][0], l[i]});
}
ans = MOD;
dfs(1);
if(ans == MOD) ans = -1;
return ans;
}
void solve() {
read(n, k);
for(int i = 1; i < n; ++i) {
read(G[i][0], G[i][1], l[i]);
G[i][0]++, G[i][1]++;
}
print(best_path(n, k, G, l));
}
int main() {
//freop("");
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t = 1;
//read(t);
for (int i = 1; i <= t; ++i) {
//write("Case #" + to_string(i) + ": ");
solve();
}
return 0;
}