Submission #1030295

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030295		12345678	Towns (IOI15_towns)	C++17	49 / 100	13 ms	980 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>

using namespace std;

int hubDistance(int N, int sub) {
	pair<int, int> mx={0, 0};
	int l=0, r, mn=INT_MAX;
	vector<int> dl(N), dr(N), dh(N);
	for (int i=1; i<N;i ++) dl[i]=getDistance(0, i), mx=max(mx, {dl[i], i});
	r=mx.second;
	dr[l]=dl[r];
	for (int i=0; i<N;i ++) if (i!=l&&i!=r) dr[i]=getDistance(r, i);
	int dist=dl[r];
	map<int, int> mp;
	map<int, vector<int>> mpd;
	for (int i=0; i<N; i++)
	{
		int x=dl[i], y=dr[i], h=(x+dist-y)/2;
        dh[i]=(x+y-dist)/2;
		if (mp.find(h)==mp.end()) mp[h]=dh[i];
		else mp[h]=max(mp[h], dh[i]);
		mpd[h].push_back(i);
	}	
	for (auto [x, a]:mp)
	{
		int mx=a;
		for (auto [y, b]:mp) mx=max(mx, abs(x-y)+b);
		mn=min(mn, mx); 
	}
	int sz=0, can=-1;
	for (auto [x, a]:mp)
	{
		int mx=a;
		for (auto [y, b]:mp) mx=max(mx, abs(x-y)+b);
		if (mn==mx) 
        {
            //cout<<"here "<<x<<' '<<sz<<' '<<mpd[x].size()<<' '<<N-sz-mpd[x].size()<<'\n';
            if (sz<=(N/2)&&(N-sz-(int)mpd[x].size()<=(N/2)))
            {
                if (((int)mpd[x].size())<=(N/2)) can=1;
                else
                {
                    int lst=0, freq=0;
                    for (auto idx:mpd[x])
                    {
                        if (freq==0)
                        {
                            freq++;
                            lst=idx;
                        }
                        else
                        {
                            if (getDistance(idx, lst)!=(dh[idx]+dh[lst])) freq++;
                            else freq--;
                        }
                    }
                    int cnt=0;
                    for (auto idx:mpd[x]) if (getDistance(lst, idx)!=(dh[idx]+dh[lst])) cnt++;
                    //cout<<"debug "<<x<<' '<<cnt<<'\n';
                    if (cnt<=(N/2)) can=1;
                }
            }
        }
        sz+=mpd[x].size();
	}
	return mn*can;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:27:7: warning: declaration of 'mx' shadows a previous local [-Wshadow]
   27 |   int mx=a;
      |       ^~
towns.cpp:7:17: note: shadowed declaration is here
    7 |  pair<int, int> mx={0, 0};
      |                 ^~
towns.cpp:34:7: warning: declaration of 'mx' shadows a previous local [-Wshadow]
   34 |   int mx=a;
      |       ^~
towns.cpp:7:17: note: shadowed declaration is here
    7 |  pair<int, int> mx={0, 0};
      |                 ^~
towns.cpp:65:25: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   65 |         sz+=mpd[x].size();
      |                         ^
towns.cpp:6:28: warning: unused parameter 'sub' [-Wunused-parameter]
    6 | int hubDistance(int N, int sub) {
      |                        ~~~~^~~

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