Submission #1090891

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090891		owoovo	Towns (IOI15_towns)	C++17	100 / 100	23 ms	1112 KiB

towns

#include "towns.h"
#include<bits/stdc++.h>
#define ll long long
#define F first 
#define S second 
using namespace std;
const ll maxn=1e18;
ll to0[120],tor1[120],tor2[120],n;
ll r1,r2;
map<pair<int,int>,int> mp;
int getd(int a,int b){
	if(a==b)return 0;
	if(mp.count({min(a,b),max(a,b)})==0){
		mp[{min(a,b),max(a,b)}]=getDistance(a,b);
	}
	return mp[{min(a,b),max(a,b)}];
}
struct DSU{
	int val[120],sz[120];
	void init(){
		for(int i=0;i<n;i++)val[i]=i,sz[i]=1;
		return;
	}
	int f(int a){
		if(a==val[a])return a;
		val[a]=f(val[a]);
		return val[a];
	}
	void onion(int a,int b){
		a=f(a);
		b=f(b);
		if(a==b)return;
		if(sz[a]>sz[b])swap(a,b);
		val[a]=b;
		sz[b]+=sz[a];
		return;
	}
}dsu;
int hubDistance(int N, int sub) {
	mp.clear();
	n=N;
	for(int i=1;i<N;i++)to0[i]=getd(0,i);
	ll maxn=0,pos=0;
	for(int i=0;i<N;i++){
		if(to0[i]>maxn){
			maxn=to0[i];
			pos=i;
		}
	}
	r1=pos;
	for(int i=0;i<N;i++)tor1[i]=getd(r1,i);
	maxn=0,pos=0;
	for(int i=0;i<N;i++){
		if(tor1[i]>maxn){
			maxn=tor1[i];
			pos=i;
		}
	}
	r2=pos;
	vector<pair<ll,ll>> vc;
	for(int i=0;i<N;i++){
		ll dis=(to0[r1]+tor1[i]-to0[i])/2;
		vc.push_back({dis,tor1[i]-dis});
	}
	ll ans=maxn;
	for(int i=0;i<N;i++){
		ans=min(ans,max(vc[i].F,tor1[r2]-vc[i].F));
	}
	vector<ll> want;
	for(int i=0;i<N;i++){
		if(ans==max(vc[i].F,tor1[r2]-vc[i].F)){
			want.push_back(vc[i].F);
		}
	}
	int ok=0;
	for(auto dis:want){
		int s=0,m=0,l=0;
		vector<int> now;
		for(int i=0;i<N;i++){
			if(vc[i].F<dis)s++;
			else if(vc[i].F==dis)now.push_back(i);
			else l++;
		}
		if(s>N/2||l>N/2)continue;
		int nx=now[0],mis=1,OK=1;
		dsu.init();
		for(int i=1,x=now[i];i<now.size();i++,x=now[i]){
			if(nx==0){
				mis=1;
				nx=now[i];
				continue;
			}
			if(getd(nx,x)<vc[nx].S+vc[x].S){
				dsu.onion(nx,x);
				mis++;
			}else{
				mis--;
			}
			if(mis==0)nx=0;
		}
		for(int i=0,x=now[i];i<now.size();i++,x=now[i]){
			if(x==dsu.f(x)){
				if(getd(nx,x)<vc[nx].S+vc[x].S){
					dsu.onion(nx,x);
				}
			}
		}
		for(int i=0,x=now[i];i<now.size();i++,x=now[i]){
			if(x==dsu.f(x)&&dsu.sz[x]>n/2){
				OK=0;
			}
		}
		ok|=OK;
	}
	return ok==1?ans:-ans;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:43:5: warning: declaration of 'maxn' shadows a global declaration [-Wshadow]
   43 |  ll maxn=0,pos=0;
      |     ^~~~
towns.cpp:7:10: note: shadowed declaration is here
    7 | const ll maxn=1e18;
      |          ^~~~
towns.cpp:51:35: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   51 |  for(int i=0;i<N;i++)tor1[i]=getd(r1,i);
      |                                   ^~
towns.cpp:87:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   87 |   for(int i=1,x=now[i];i<now.size();i++,x=now[i]){
      |                        ~^~~~~~~~~~~
towns.cpp:101:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |   for(int i=0,x=now[i];i<now.size();i++,x=now[i]){
      |                        ~^~~~~~~~~~~
towns.cpp:108:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  108 |   for(int i=0,x=now[i];i<now.size();i++,x=now[i]){
      |                        ~^~~~~~~~~~~
towns.cpp:77:11: warning: unused variable 'm' [-Wunused-variable]
   77 |   int s=0,m=0,l=0;
      |           ^
towns.cpp:115:14: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
  115 |  return ok==1?ans:-ans;
      |         ~~~~~^~~~~~~~~
towns.cpp:39:28: warning: unused parameter 'sub' [-Wunused-parameter]
   39 | 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