Submission #593671

#	Time	Username	Problem	Language	Result	Execution time	Memory
593671		Deepesson	Towns (IOI15_towns)	C++17	35 / 100	19 ms	1104 KiB

towns

#include <bits/stdc++.h>
#define MAX 115
int getDistance(int i, int j);
int hubDistance(int N, int sub);
typedef std::pair<int,int> pii;
std::map<pii,int> memoria;
int count=0;
int smartgetDistance(int a, int b){
    if(a==b)return 0;
    if(a>b)std::swap(a,b);
    pii x = {a,b};
    if(memoria.find(x)!=memoria.end())return memoria[x];
    int d = getDistance(a,b);
    memoria[x]=d;
    ++count;
    return d;
}

int dist[MAX][2];
pii MaisDistante(int N,int x,int p){
    int best=-1,alvo=0;
    for(int i=0;i!=N;++i){
        if(i==x)continue;
        int d = smartgetDistance(i,x);
        if(d>best){
            best=d;
            alvo=i;
        }
        dist[i][p]=d;
    }
    return {best,alvo};
}
int dist_centro[MAX];
///Queries usadas: 3N-3
bool mesma_subarvore(int a,int b){
    if(a==b)return 1;
    return smartgetDistance(a,b)==dist_centro[a]+dist_centro[b];
}
int hubDistance(int N, int sub) {
    count=0;
    memoria.clear();
	pii alpha = MaisDistante(N,0,1);
	pii beta = MaisDistante(N,alpha.second,0);
	MaisDistante(N,beta.second,1);
	int d = beta.first;
	int ans=1e9;
	int exp_a=0,exp_b=0;
	std::map<pii,bool> hubs;
	for(int i=0;i!=N;++i){
        if(i==alpha.second||i==beta.second)continue;
        int a = dist[i][0];
        int b = dist[i][1];
        int soma = a+b;
        int subt = soma-d;
        int base = subt/2;
        int custo = std::max(a,b)-base;
        exp_a = a-base;
        exp_b = b-base;
        if(custo<ans){///Fora da sub de A ou B
            ans=custo;
            hubs.clear();
            hubs[{exp_a,exp_b}]=true;
        }else if(custo==ans)hubs[{exp_a,exp_b}]=true;

        dist_centro[i]=base;
	}
	if(sub<=2)return ans;
	int c=0;
	assert(hubs.size()<=2);
	for(auto&z:hubs){
        exp_a = z.first.first;
        exp_b = z.first.second;
        std::vector<int> fora;
        int grupos[2]={1,1};
        for(int i=0;i!=N;++i){
            if(i==alpha.second||i==beta.second)continue;
            int a = dist[i][0];
            int b = dist[i][1];
            int soma = a+b;
            int subt = soma-d;
            int base = subt/2;
            int dist_a = a-base;
            int dist_b = b-base;
            if(dist_a == exp_a && dist_b == exp_b){///Fora da sub de A ou B
                fora.push_back(i);
            }else {///Na subarvore de A ou B
                if(a>b)grupos[0]++;else grupos[1]++;
            }
        }
        int lim=N/2;
        if(grupos[0]>lim||grupos[1]>lim)goto fail;
        ++c;
        if(c>1)assert(0);
        ///Executa APENAS 1 vez
        ///Para a sub 4
        if(sub==4){
            int sum = N-(grupos[0]+grupos[1]);
            if(sum>lim)goto fail;
            return ans;
        }
        ///Achei o erro:
        ///Pode ter mais de um hub
        ///E ele quer saber se qq um deles eh balanceado
        assert(fora.size()==(N-(grupos[0]+grupos[1])));
        {
            std::vector<int> vec;
            for(int i=0;i!=fora.size();++i){
                if(!vec.size())vec.push_back(fora[i]);
                {
                    if(mesma_subarvore(vec.back(),fora[i])){
                        vec.push_back(fora[i]);
                    }else vec.pop_back();
                }
            }
            if(vec.size()){
                int count=0;
                for(auto&x:fora)if(mesma_subarvore(x,vec.back()))++count;
                if(count>lim)return -ans;
                return ans;
            }else return ans;
        }
        return ans;
        fail:{}
	}
	return -ans;
}

Compilation message (stderr)

In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from towns.cpp:1:
towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:104:27: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  104 |         assert(fora.size()==(N-(grupos[0]+grupos[1])));
      |                ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
towns.cpp:107:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  107 |             for(int i=0;i!=fora.size();++i){
      |                         ~^~~~~~~~~~~~~
towns.cpp:116:21: warning: declaration of 'count' shadows a global declaration [-Wshadow]
  116 |                 int count=0;
      |                     ^~~~~
towns.cpp:7:5: note: shadowed declaration is here
    7 | int count=0;
      |     ^~~~~

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