# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
379293 | justiny7 | 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 "race.h"
#include <bits/stdc++.h>
using namespace std;
const int mxN=2e5+1, mxK=1e6+1, INF=1e9;
int ans=INF, sz[mxN], mn[mxN];
vector<pair<int, int>> adj[mxN];
bool vis[mxN];
int dfs_sz(int v, int p=-1) {
sz[v]=1;
for (auto [u, d]:adj[v])
if (!vis[u] && u^p)
sz[v]+=dfs_sz(u, v);
return sz[v];
}
int dfs_centroid(int tot, int v, int p=-1) {
for (auto [u, d]:adj[v])
if (!vis[u] && u^p && sz[u]*2>tot)
return dfs_centroid(tot, u, v);
return v;
}
void dfs(int k, int v, int p=-1, int dep=0, int len=0) {
mn[len]=min(mn[len], dep);
for (auto [u, d]:adj[v])
if (!vis[u] && u^p && len+d<=k)
dfs(k, u, v, dep+1, len+d);
}
void decomp(int k, int x=0) {
int v=dfs_centroid(dfs_sz(x), x);
vis[v]=1;
fill(mn+1, mn+k+1, INF);
dfs(k, v);
for (int i=0; i<=k/2; ++i)
ans=min(ans, mn[i]+mn[k-i]);
for (auto [u, d]:adj[v])
if (!vis[u])
decomp(k, u);
}
int best_path(int N, int K, vector<vector<int>> H, vector<int> L) {
for (int i=0; i<N; ++i)
adj[i].clear();
for (int i=0; i<N-1; ++i) {
adj[H[i][0]].emplace_back(H[i][1], L[i]);
adj[H[i][1]].emplace_back(H[i][0], L[i]);
}
decomp(K);
return (ans==INF?-1:ans);
}