Submission #1087211

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087211		guagua0407	Towns (IOI15_towns)	C++17	25 / 100	10 ms	528 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);



int hubDistance(int N, int sub) {
    int n=N;
    vector<vector<int>> rec(n,vector<int>(n,-1));
    function<int(int,int)> get=[&](int a,int b){
        if(a==b) return 0;
        if(a>b) swap(a,b);
        if(rec[a][b]!=-1) return rec[a][b];
        else{
            rec[a][b]=getDistance(a,b);
            return rec[a][b];
        }
    };
    vector<int> dis(n),dis2(n);
    for(int i=0;i<n;i++){
        dis2[i]=get(0,i);
    }
    int x=max_element(all(dis2))-dis2.begin();
    for(int i=0;i<n;i++){
        dis[i]=get(x,i);
    }
    int R=*max_element(all(dis));
    int y=0;
    vector<int> val1(n),val2(n);
    vector<int> vec;
    for(int i=0;i<n;i++){
        vec.push_back(dis[i]-(dis[i]+dis2[i]-dis[y])/2);
        val1[i]=dis[i]-(dis[i]+dis2[i]-dis[y])/2;
        val2[i]=(dis[i]+dis2[i]-dis[y])/2;
    }
    sort(all(vec));
    int ans=R;
    for(auto v:vec){
        ans=min(ans,max(v,R-v));
    }
    map<int,int> mp;
    for(auto v:vec){
        mp[v]++;
    }
    bool tf=false;
    int pre=0;
    for(auto v:mp){
        if(max(v.f,R-v.f)==ans){
            int mx=max({pre,v.s,n-pre-v.s});
            if(mx<=n/2){
                tf=true;
            }
        }
        pre+=v.s;
    }
    function<bool(int,int)> same=[&](int a,int b){
        int d=get(a,b);
        return (d==(val2[a]+val2[b]));
    };
    if(!tf){
        pre=0;
        for(auto v:mp){
            if(max(v.f,R-v.f)==ans){
                if(v.s>n/2){
                    vector<pair<int,int>> diaob,roy,tmp;
                    for(int i=0;i<n;i++){
                        if(val1[i]==v.f){
                            diaob.push_back({i,1});
                        }
                    }
                    while((int)diaob.size()>1){
                        for(int i=0;i<(int)diaob.size()-1;i+=2){
                            if(diaob[i].s<diaob[i+1].s) swap(diaob[i],diaob[i+1]);
                            if(same(diaob[i].f,diaob[i+1].f)){
                                tmp.push_back({diaob[i].f,diaob[i].s+diaob[i+1].s});
                            }
                            else{
                                roy.push_back({diaob[i].f,diaob[i+1].s});
                                roy.push_back(diaob[i+1]);
                                if(diaob[i].s>diaob[i+1].s){
                                    tmp.push_back({diaob[i].f,diaob[i].s-diaob[i+1].s});
                                }
                            }
                        }
                        if((int)diaob.size()&1) tmp.push_back(diaob.back());
                        swap(diaob,tmp);
                        tmp.clear();
                    }
                    if(diaob.empty()){
                        tf=true;
                    }
                    else{
                        int cnt=diaob[0].s;
                        int node=diaob[0].f;
                        for(auto u:roy){
                            if(same(node,u.f)) cnt+=u.s;
                        }
                        if(cnt<=n/2){
                            tf=true;
                        }
                        else{
                            tf=false;
                        }
                    }
                    break;
                }
            }
            pre+=v.s;
        }
    }
	return (tf?ans:-ans);
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:29:33: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   29 |     int x=max_element(all(dis2))-dis2.begin();
      |           ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
towns.cpp:13:28: warning: unused parameter 'sub' [-Wunused-parameter]
   13 | int hubDistance(int N, int sub) {
      |                        ~~~~^~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39