Submission #1039643

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039643		vjudge1	Highway Tolls (IOI18_highway)	C++17	51 / 100	118 ms	13356 KiB

highway

#include "highway.h"
#include<bits/stdc++.h>
#define K 1<<17
using namespace std;
int bfspos[2][K],CC,bfspar[2][K],bfspari[2][K],bfsdis[2][K];
vector<pair<int,int>>adj[K];
void bfs(int n,int i){
    queue<int>q;
    int CC=0;
    memset(bfsdis[i],-1,sizeof *bfspos);
    q.push(n);
    bfsdis[i][n]=0;
    bfspar[i][n]=-1;
    while(q.size()){
        int x=q.front(),d=bfsdis[i][x];
        q.pop(); bfspos[i][x]=++CC;
        for(auto [j,k]:adj[x]) if(bfsdis[i][j]<0)
            bfspar[i][j]=x,bfspari[i][j]=k,
            bfsdis[i][j]=d+1,q.push(j);
    }
}
int indd;
int whicho(int pivot,int N,int ind,int M,vector<int>v,long long D,int spec){
    indd=ind;
    sort(v.begin(),v.end(),[](int a,int b){
        return bfspos[indd][a]<bfspos[indd][b];
    });
    int l=1,r=v.size()-1,res=1;
    while(l<=r){
        int mid=l+r>>1;
        vector<int>V(M,1);
        V[spec]=0;
        for(int i=mid;i<v.size();i++) {
            if(bfspar[ind][v[i]]!=pivot)
                if(!V[bfspari[ind][bfspar[ind][v[i]]]])
                    continue;
            V[bfspari[ind][v[i]]]=0;
        }
        if(ask(V)<D)
            l=res=mid+1;
        else r=mid-1;
    }
    return v[res-1];
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    int M=U.size();
    for(int i=0;i<M;i++)
        adj[U[i]].push_back({V[i],i}),
        adj[V[i]].push_back({U[i],i});
    long long D=ask(vector<int>(M,0))/A;
    int res=1e9,l=1,r=M-1;
    while(l<=r){
        int mid=l+r>>1;
        vector<int>v(M);
        for(int i=0;i<mid;i++)
            v[i]=1;
        if(ask(v)>D*A)
            res=r=mid-1;
        else l=mid+1;
    }
    int a=U[res],b=V[res];
    bfs(a,0);
    bfs(b,1);
    vector<int>sta,stb;
    for(int i=0;i<N;i++)
        if(bfsdis[0][i]<bfsdis[1][i])
            sta.push_back(i);
        else if(bfsdis[0][i]-bfsdis[1][i])
            stb.push_back(i);
    answer(whicho(a,N,0,M,sta,D*B-B+A,res),
            whicho(b,N,1,M,stb,D*B-B+A,res));
}

Compilation message (stderr)

highway.cpp: In function 'int whicho(int, int, int, int, std::vector<int>, long long int, int)':
highway.cpp:30:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   30 |         int mid=l+r>>1;
      |                 ~^~
highway.cpp:33:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |         for(int i=mid;i<v.size();i++) {
      |                       ~^~~~~~~~~
highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:53:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   53 |         int mid=l+r>>1;
      |                 ~^~

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