# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
250327 | Osama_Alkhodairy | Highway Tolls (IOI18_highway) | 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>
//~ #include "highway.h"
#include "grader.cpp"
using namespace std;
#define ll long long
int n, m;
vector <pair <int, int> > es, g[90001];
ll light;
int dist;
int find(int root, bool b){
vector <bool> vis(n);
queue <int> ready;
vector <int> depth(n);
ready.push(root);
vector <int> nodes;
vis[root] = 1;
while(ready.size()){
int node = ready.front();
ready.pop();
nodes.push_back(node);
for(auto &i : g[node]){
if(vis[i.first]) continue;
vis[i.first] = 1;
depth[i.first] = depth[node] + 1;
ready.push(i.first);
}
}
if(b){
while(depth[nodes.back()] != dist){
nodes.pop_back();
}
}
reverse(nodes.begin(), nodes.end());
if(b){
while(depth[nodes.back()] != dist){
nodes.pop_back();
}
}
while(depth[nodes.back()] < dist / 2){
nodes.pop_back();
}
int l = 0, r = (int)nodes.size() - 1;
while(l <= r){
int mid = (l + r) / 2;
vector <int> check(m), vis(m);
for(int i = 0 ; i <= mid ; i++){
for(auto &j : g[nodes[i]]){
if(vis[j.second]) continue;
vis[j.second] = 1;
check[j.second] = 1;
}
}
if(ask(check) != light) r = mid - 1;
else l = mid + 1;
}
return nodes[l];
}
void find_pair(int N, std::vector<int> u, std::vector<int> v, int a, int b) {
n = N;
m = u.size();
for(int i = 0 ; i < m ; i++){
g[u[i]].push_back(make_pair(v[i], i));
g[v[i]].push_back(make_pair(u[i], i));
es.push_back(make_pair(u[i], v[i]));
}
light = ask(vector <int>(m, 0));
dist = light / a;
int l = 0, r = m - 1;
while(l <= r){
int mid = (l + r) / 2;
vector <int> check(m);
for(int i = 0 ; i <= mid ; i++){
check[i] = 1;
}
if(ask(check) != light) r = mid - 1;
else l = mid + 1;
}
int root = es[l].first;
int s = find(root, 0);
int t = find(s, 1);
answer(s, t);
}