Submission #592238

#	Time	Username	Problem	Language	Result	Execution time	Memory
592238		Deepesson	Towns (IOI15_towns)	C++17	23 / 100	18 ms	484 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 smartgetDistance(int a, int b){
    if(a>b)std::swap(a,b);
    if(a==b)return 0;
    if(memoria.find({a,b})!=memoria.end())return memoria[{a,b}];
    int d = getDistance(a,b);
    memoria[{a,b}]=d;
    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
int hubDistance(int N, int sub) {
    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 eixo;
	int exp_a,exp_b;
	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;
        dist_centro[i]=base;
        if(custo<ans){///Fora da sub de A ou B
            eixo=i;
            ans=custo;
            exp_a = a-base;
            exp_b = b-base;
        }
	}
	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 custo = std::max(a,b)-base;
        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)return -ans;
	///Para a sub 4
	if(sub==4){
        int sum = N-(grupos[0]+grupos[1]);
        if(sum>lim)return -ans;
        return ans;
	}
	assert(fora.size()==(N-(grupos[0]+grupos[1])));
	std::vector<pii> opcoes;
	for(auto&x:fora){
        bool ok=false;
        for(int i=0;i!=opcoes.size();++i){
            int p = opcoes[i].first;
            if(smartgetDistance(p,x)!=(dist_centro[x]+dist_centro[p])){
                ++opcoes[i].second;
                if(opcoes[i].second>lim)return -ans;
                assert(!ok);
                ok=true;
            }
        }
        if(!ok)
        opcoes.push_back({x,1});
        safe:{}
	}
	return ans;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:66:13: warning: unused variable 'custo' [-Wunused-variable]
   66 |         int custo = std::max(a,b)-base;
      |             ^~~~~
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:83:20: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   83 |  assert(fora.size()==(N-(grupos[0]+grupos[1])));
      |         ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
towns.cpp:87:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   87 |         for(int i=0;i!=opcoes.size();++i){
      |                     ~^~~~~~~~~~~~~~~
towns.cpp:39:6: warning: variable 'eixo' set but not used [-Wunused-but-set-variable]
   39 |  int eixo;
      |      ^~~~
towns.cpp:98:9: warning: label 'safe' defined but not used [-Wunused-label]
   98 |         safe:{}
      |         ^~~~
towns.cpp:69:38: warning: 'exp_b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   69 |         if(dist_a == exp_a && dist_b == exp_b){///Fora da sub de A ou B
      |                               ~~~~~~~^~~~~~~~
towns.cpp:69:19: warning: 'exp_a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   69 |         if(dist_a == exp_a && dist_b == exp_b){///Fora da sub de A ou B
      |            ~~~~~~~^~~~~~~~

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