Submission #966147

#	Time	Username	Problem	Language	Result	Execution time	Memory
966147		Warinchai	Highway Tolls (IOI18_highway)	C++14	51 / 100	136 ms	15248 KiB

highway

#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
vector<pair<int,int>>adj[100000];
void dfs(int u,vector<int>&x,vector<int>&nodes,int p,int val){
    x.push_back(val);
    nodes.push_back(u);
    for(auto v:adj[u])if(v.first!=p)dfs(v.first,x,nodes,u,v.second);
}
void subtree(int n,vector<int>u,vector<int>v,int a,int b,long long cost){
    //cerr<<"work\n";
    int st=0,en=u.size()-1,ans=0;
    while(st<=en){
        int m=(st+en)/2;
        //cerr<<"m:"<<m<<"  ";
        vector<int>temp;
        for(int i=0;i<=m;i++)temp.push_back(1);
        for(int i=m+1;i<n-1;i++)temp.push_back(0);
      //  cerr<<temp.size()<<"\n";
        long long tcost=ask(temp);
        //cerr<<tcost<<"\n";
        if(tcost>cost){
            en=m-1;
            ans=m;
        }else{
            st=m+1;
        }
    }
    int bg=u[ans];
    int ed=v[ans];
    //cerr<<bg<<" "<<ed<<"\n";
    vector<int>temp;
    vector<int>side1;
    vector<int>side2;
    vector<int>node1;
    vector<int>node2;
    for(int i=0;i<n-1;i++)temp.push_back(0);
    //temp[ans]=1;
    //assert(ask(temp)>cost);
    dfs(bg,side1,node1,ed,ans);
    dfs(ed,side2,node2,bg,ans);
    for(auto x:side1)temp[x]=1;
    long long cost1=ask(temp);
    for(auto x:side1)temp[x]=0;
    for(auto x:side2)temp[x]=1;
    long long cost2=ask(temp);
    for(int i=0;i<n-1;i++)temp[i]=0;
    int n1,n2;
    st=0,en=side1.size()-1;
    for(int i=0;i<n-1;i++)temp[i]=0;
  //  cerr<<"side1\n";
    //for(auto x:side1)cerr<<x<<" ";
//    cerr<<"\n";
    //cerr<<"side2\n";
    //for(auto x:side2)cerr<<x<<" ";
    //cerr<<"\n\n";
    while(st<=en){
        int m=(st+en)/2;
        for(int i=0;i<=m;i++)temp[side1[i]]=1;
        if(ask(temp)>=cost1){
            en=m-1;
            n1=m;
        }else{
            st=m+1;
        }
        for(int i=0;i<=m;i++)temp[side1[i]]=0;
    }
    st=0,en=side2.size()-1;
    while(st<=en){
        int m=(st+en)/2;
        for(int i=0;i<=m;i++)temp[side2[i]]=1;
        if(ask(temp)>=cost2){
            en=m-1;
            n2=m;
        }else{
            st=m+1;
        }
        for(int i=0;i<=m;i++)temp[side2[i]]=0;
    }
    //cerr<<node1[n1]<<" "<<node2[n2]<<"\n";
    answer(node1[n1],node2[n2]);
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    //cerr<<"work\n";
    for(int i=0;i<U.size();i++){
        adj[U[i]].push_back({V[i],i});
        adj[V[i]].push_back({U[i],i});
    }
    vector<int>temp;
    for(int i=0;i<N-1;i++)temp.push_back(0);
    if(U.size()!=N-1)return answer(rand()%N,rand()%N);
    else return subtree(N,U,V,A,B,ask(temp));
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:85:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |     for(int i=0;i<U.size();i++){
      |                 ~^~~~~~~~~
highway.cpp:91:16: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   91 |     if(U.size()!=N-1)return answer(rand()%N,rand()%N);
      |        ~~~~~~~~^~~~~
highway.cpp: In function 'void subtree(int, std::vector<int>, std::vector<int>, int, int, long long int)':
highway.cpp:81:30: warning: 'n2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   81 |     answer(node1[n1],node2[n2]);
      |                              ^
highway.cpp:81:20: warning: 'n1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   81 |     answer(node1[n1],node2[n2]);
      |                    ^

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31