# | Submission time | Handle | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1055493 | 2024-08-12T20:06:37 Z | Ahmed57 | Highway Tolls (IOI18_highway) | C++17 | 0 ms | 0 KB |
#include "bits/stdc++.h" #include "highway.h" using namespace std; #define int long long pair<int,int> p[100001]; int dep[100001]; vector<pair<int,int>> adj[100001]; void dfs(int i){ queue<int> q; q.push(0); dep[0] = 1; p[0] = {0,-1}; while(!q.empty()){ int f = q.front();q.pop(); for(auto j:adj[f]){ if(dep[j.first]==0){ dep[j.first] = dep[f]+1; p[j.first] = {f,j.second}; q.push(j.first); } } } } void find_pair(int32_t N, vector<int32_t> U, vector<int32_t> V, int32_t A, int32_t B){ int m = U.size(); int n = N; vector<int32_t> as(m,0); int len = ask(as); for(int i = 0;i<U.size();i++){ adj[U[i]].push_back({V[i],i}); adj[V[i]].push_back({U[i],i}); } int l = 0 ,r = n-1 , ans = 0; while(l<=r){ int mid = (l+r)/2; vector<int32_t> as(m,0); for(int i = mid+1;i<n;i++){ for(auto j:adj[i]){ as[j.second] = 1; } } if(ask(as)==len){ ans = mid; r = mid-1; }else l = mid+1; } dfs(ans); vector<pair<int,int>> v; for(int i = 0;i<N;i++){ v.push_back({dep[i],i}); } sort(v.begin(),v.end()); int l = 1 , r = n-1 , ans2 = 0; while(l<=r){ int mid = (l+r)/2; vector<int32_t> as(m,1); for(int i = 1;i<=mid;i++){ as[p[v[i].second].second] =0 ; } if(ask(as)==len){ ans2 = mid; r = mid-1; }else l = mid+1; } int a = v[ans2].second; l = 0 , r = ans2-1 ; int ans3 = 0; while(l<=r){ int mid = (l+r)/2; vector<int32_t> as(m,1); for(int i = 1;i<=mid;i++){ as[p[v[i].second].second] = 0; } int f = a; while(p[f].second!=-1){ as[p[f].second] = 0; f = p[f].first; } if(ask(as)==len){ ans3 = mid; r = mid-1; }else l = mid+1; } int b = v[ans3].second; answer(a,b); }