| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 484920 | wind_reaper | 경주 (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.
#include <bits/stdc++.h>
#ifndef LOCAL
#include "race.h"
#endif
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
*/
using namespace std;
// using namespace __gnu_pbds;
using namespace chrono;
// mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
/*
template <class T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
*/
//***************** CONSTANTS *****************
const int MXN = 100000;
//***************** GLOBAL VARIABLES *****************
vector<array<int, 2>> g[MXN];
int mp[1000001];
int ans = INT_MAX, K, sz[MXN], r[MXN];
int64_t depth[MXN];
//***************** AUXILIARY STRUCTS *****************
int dfs(int p, int u){
sz[u] = 1;
for(auto& [v, d] : g[u]) if(v != p){
sz[u] += dfs(u, v);
}
return sz[u];
}
void dfs2(int p, int u, int s, int len){
if(depth[u] > K)
return;
mp[s][depth[u]] = min(mp[s][depth[u]], len);
for(auto& [v, d] : g[u]) if(v != p && !r[v]){
depth[v] = depth[u] + int64_t(d);
dfs2(u, v, s, len + 1);
}
}
void decompose(int u){
int inv = -1, lim = sz[u] >> 1;
for(auto& [v, d] : g[u])
if(!r[v] && sz[v] > lim){
inv = v;
break;
}
if(inv != -1){
sz[u] -= sz[inv];
sz[inv] += sz[u];
decompose(inv);
return;
}
r[u] = 1;
depth[u] = 0;
fill(mp[u], mp[u] + 1000001, MXN + 1);
for(auto& [v, d] : g[u]) if(!r[v]){
depth[v] = d;
fill(mp[v], mp[v] + 1000001, MXN + 1);
dfs2(u, v, v, 1);
}
mp[u][0] = 0;
for(auto& [v, d] : g[u]) if(!r[v]){
for(auto& [dep, len] : mp[v]){
if(dep <= K) ans = min(ans, len + mp[u][K - dep]);
}
for(auto& [dep, len] : mp[v]){
if(dep > K)
continue;
mp[u][dep] = min(mp[u][dep], len);
}
}
for(auto& [v, d] : g[u]) if(!r[v]){
decompose(v);
}
}
//***************** MAIN BODY *****************
int best_path(int N, int k, int H[][2], int L[]){
for(int i = 0; i < N - 1; i++){
g[H[i][0]].push_back({H[i][1], L[i]});
g[H[i][1]].push_back({H[i][0], L[i]});
}
K = k;
dfs(0, 0);
decompose(0);
return (ans == INT_MAX ? -1 : ans);
}
//***************** *****************
#ifdef LOCAL
int32_t main(){
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
#ifdef LOCAL
auto begin = high_resolution_clock::now();
#endif
int tc = 1;
// cin >> tc;
for (int t = 0; t < tc; t++){
int N, k;
cin >> N >> k;
int H[N-1][2], L[N-1];
for(int i = 0; i < N-1; i++)
cin >> H[i][0] >> H[i][1] >> L[i];
cout << best_path(N, k, H, L) << '\n';
}
#ifdef LOCAL
auto end = high_resolution_clock::now();
cout << fixed << setprecision(4);
cout << "Execution Time: " << duration_cast<duration<double>>(end - begin).count() << "seconds" << endl;
#endif
return 0;
}
#endif
/*
If code gives a WA, check for the following :
1. I/O format
2. Are you clearing all global variables in between tests if multitests are a thing
3. Can you definitively prove the logic
4. If the code gives an inexplicable TLE, and you are sure you have the best possible complexity,
use faster io
*/