| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 604161 | PiejanVDC | 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 "highway.h"
#include <bits/stdc++.h>
using namespace std;
const int mxN = (int)9e4+5;
int def;
long long normal;
int N_;
mt19937 mt(time(nullptr));
long long ask(const std::vector<int> &w);
void answer(int s, int t);
map<pair<int,int>, int>id;
vector<int>re(mxN);
int search_point(vector<int>points) {
int n = (int)points.size();
int ans = -1;
int l = 0, r = n-1;
while(l <= r) {
if(l == r && ans == -1) {
ans = l;
break;
}
int mid = (l+r)/2;
vector<int>Ask(N_, 0);
for(int i = l ; i <= mid ; i++)
Ask[points[i]] = 1;
if(ask(Ask) != normal) {
r = mid-1;
ans = mid;
} else l = mid+1;
}
return points[ans];
}
bool present(vector<int>points) {
vector<int>Ask(N_, 0);
for(auto z : points)
Ask[z] = 1;
return ask(Ask) != normal;
}
vector<int>p[mxN];
vector<int>parent(mxN);
vector<int>adj[mxN];
int mxDist;
int A_ = -2;
int h = -2;
void dfs(int node, int dist, int e = -1) {
if(node == h) return;
mxDist = max(mxDist, dist);
if(e > -1) p[dist].push_back(id[{node, e}]);
parent[node] = e;
re[node] = dist;
for(auto z : adj[node]) if(z != e) dfs(z, dist+1, node);
}
int distance() {
int l = 1, r = mxDist;
int ans = -1;
while(l <= r) {
int mid = (l+r)/2;
if(present(p[mid]))
ans = mid, l = mid+1;
else
r = mid-1;
}
return ans;
}
void delete_(int a) {
if(a == def) return;
for(int i = 0 ; i <= mxDist ; i++)
p[i].clear();
stack<int>s;
s.push(a);
vector<bool>vis(N_+1, 0);
vis[a] = 1;
while(1) {
int node = s.top();
s.pop();
for(auto z : adj[node]) if(!vis[z]) {
if(z == def) {
h = node;
return;
}
vis[z] = 1;
s.push(z);
}
}
}
int Check = 1;
void check() { /*cout << "Check " << Check++ << '\n';*/ }
int num_calls;
void find_pair(int n, vector<int>u, vector<int>v, int a_, int b_) {
N_ = n-1;
vector<int>dummy(n-1, 0);
normal = ask(dummy);
vector<int>rev(n-1);
for(int i = 0 ; i < n-1 ; i++)
id[{u[i], v[i]}] = id[{v[i], u[i]}] = i, rev[i] = u[i], adj[u[i]].push_back(v[i]), adj[v[i]].push_back(u[i]);
vector<int>d(n);
for(int i = 0 ; i < n ; i++)
d[i] = i;
random_shuffle(d.begin(), d.end(), mt);
def = rev[search_point(d)];
dfs(def, 0);
int a = distance();
if(a == -1)
A_ = def;
else {
random_shuffle(p[a].begin(), p[a].end(), mt);
A_ = search_point(p[a]);
A_ = (re[u[A_]] > re[v[A_]] ? u[A_] : v[A_]);
}
delete_(A_);
mxDist = 0;
dfs(def, 0);
long long need = normal / a_ - max(0, a);
int b = need;
int B_ = -1;
if(b == 0)
B_ = def;
else {
random_shuffle(p[b].begin(), p[b].end(), mt);
B_ = search_point(p[b]);
B_ = (re[u[B_]] > re[v[B_]] ? u[B_] : v[B_]);
}
answer(A_, B_);
}