Submission #134867

#	Time	Username	Problem	Language	Result	Execution time	Memory
134867		nvmdava	Towns (IOI15_towns)	C++17	100 / 100	22 ms	504 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;

int d[2][115], v;
map<int, int> cntr;
int hubDistance(int N, int sub) {
	memset(d, 0, sizeof d);
	cntr.clear();
	for(int i = 0; i < N; i++)
		if(d[0][v] < (d[0][i] = getDistance(0, i)))
			v = i;

	int T = d[0][v], D = 0;
	for(int i = 0; i < N; i++)
		D = max(D, d[1][i] = getDistance(v, i));
	int r = 1000000000;

	for(int i = 0; i < N; i++){
		int s = (T + d[1][i] - d[0][i]) >> 1;
		cntr[s]++;
		r = min(r, max(s, D - s));
	}

	int chk = -1, l = 0;

	for(auto& x : cntr){
		if(l <= N / 2 && N - (l += x.ss) <= N / 2){
			if(max(x.ff, D - x.ff) == r){
				if(x.ss <= N / 2) return r;
				chk = x.ff << 1;
			}
		}
	}

	if(chk == -1) return -r;
	vector<vector<int> > s, t, de;
	vector<int> la;
	for(int i = 0; i < N; i++)
		if(chk == T + d[1][i] - d[0][i])
			s.push_back({i});

	while(s.size() > 1){
		for(int i = 1; i < s.size(); i += 2){
			if(getDistance(s[i - 1][0], s[i][0]) == d[0][s[i - 1][0]] + d[1][s[i][0]] - T){
				de.push_back(s[i - 1]);
				de.push_back(s[i]);
			} else {
				for(int& x : s[i - 1])
					s[i].push_back(x);
				t.push_back(s[i]);
			}
		}
		if(s.size() & 1){
			de.push_back(s.back());
			la = s.back();
		}
		swap(s, t);
		t.clear();
	}

	int sz = 0;
	if(s.empty()) s.push_back(la);
	else sz = s[0].size();
	if(s[0].empty()) return r;
	for(auto& x : de){
		if(getDistance(x[0], s[0][0]) != d[0][s[0][0]] + d[1][x[0]] - T)
			sz += x.size();
	}

	
	if(sz > N / 2) return -r;
	return r;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 1; i < s.size(); i += 2){
                  ~~^~~~~~~~~~
towns.cpp:66:21: warning: conversion to 'int' from 'std::vector<int>::size_type {aka long unsigned int}' may alter its value [-Wconversion]
  else sz = s[0].size();
            ~~~~~~~~~^~
towns.cpp:70:17: warning: conversion to 'int' from 'std::vector<int>::size_type {aka long unsigned int}' may alter its value [-Wconversion]
    sz += x.size();
                 ^
towns.cpp:9:28: warning: unused parameter 'sub' [-Wunused-parameter]
 int hubDistance(int N, int sub) {
                            ^~~

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