Submission #225803

#	Time	Username	Problem	Language	Result	Execution time	Memory
225803		CaroLinda	Building Skyscrapers (CEOI19_skyscrapers)	C++11	61 / 100	3626 ms	791208 KiB

skyscrapers

#include <bits/stdc++.h>

#define debug printf
#define all(x) x.begin(),x.end()
#define lp(i,a,b) for(int i = a ; i< b ; i++)
#define ss second
#define ff first
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define mk make_pair

const int MAX = 1e7+10 ;
const int MAXN = 150100 ;
const int inf = 1e9+10 ;

using namespace std ;

int N , T , idx ;
int X[MAX] , Y[MAX] , vet[MAXN] , pai[MAX] , pai_aux[MAXN] ;
int dx[8] = { 1,-1,0,0, 1,-1,1,-1 } , dy[8] = { 0,0,1,-1, -1,1, 1, -1} ;
int dx_cyclic[8] = { -1 , -1 , 0 , 1 , 1 ,1 , 0, -1 } , dy_cyclic[8] = { 0 , -1 , -1 , -1, 0 , 1 , 1 ,1  } ;
pii id[MAX] ;
bool is_full[MAX] , reachable[MAX] , checked[MAX] ;
map< pii , int > mp ;
set<int> s ;
vector<int> ans , fila ;
vector<int> componente[MAX] , adj[MAX] , adj_cyclic[MAX] ;
set<int>::iterator it ;

// ------------------------------------------------

int get_code(int x, int y)
{

    if( mp.find( mk(x,y) ) == mp.end() ) return 0 ;
    return mp.find( mk(x,y) )->ss ;

}

int find(int x)
{
    if( x == pai[x] ) return x ;
    return pai[x] = find( pai[x] ) ;
}


bool identify_articulation(int name)
{
    int j = -1 ;
    vector<int> group ;

    lp(i,0,8)
        if( is_full[ adj_cyclic[name][i] ] ) { j = i ; break ; }

    if( j == -1 ) return false ;

    int beg = -1, en = beg , times = 0 ;

    for(int i = (j+1)%8 ; true ; i = (i+1)%8 )
    {

        if( i == ((j+1)%8) && times == 1 ) break ;
        else if( i == ((j+1)%8) && times == 0 ) times ++ ;

        int c = adj_cyclic[name][i] ;

        if( is_full[c] )
        {

            if( beg == -1 ) continue ;
            if( beg % 2 == 1 && en == beg )  { beg = -1 ; continue ; }
            group.pb( find( adj_cyclic[name][beg] ) ) ;
            beg = -1 ;
            continue ;
        }

        if( beg == -1 ) beg = en = i ;
        else en = i ;

    }

    sort(all(group) ) ;

    for(int i = 1 ; i < group.size() ; i++ )
        if( group[i] == group[i-1] ) return true ;

    return false ;

}

bool identify_infinity(int name)
{
    lp(i,0,4)
    {
        int c = adj[name][i] ;
        if(c != 0 && reachable[ find(c) ]) return true ;
    }

    return false ;

}
bool check(int i) { return ( !identify_articulation(i) )&identify_infinity(i) ; }

inline void to_change(int name)
{

    for(int i = 0 ; i < 8 ; i++ )
    {

        int c = adj[name][i] ;

        if( c == 0 || !is_full[c] ) continue ;

        if( check(c) && !checked[c] )
        {
            s.insert(c) ;
            checked[c] = true ;
        }
        else if( !check(c) && checked[c] )
        {
            s.erase( s.find(c) ) ;
            checked[c] = false ;
        }

    }

}

bool join(int a, int b, bool ok )
{

    a = find(a) ;
    b = find(b) ;

    if(a==b) return false ;

    if( componente[a].size() > componente[b].size() ) swap( a , b  );

    pai[a] = b ;
    if( !reachable[b] && reachable[a] )
    {

        reachable[b] = true ;
        if(ok) for(int i : componente[b] ) fila.pb(i) ;
    }

    for( int i : componente[a] )
    {
        componente[b].pb(i) ;
        if( ok ) fila.pb(i) ;
    }
    componente[a].clear() ;

    for(int i : fila ) to_change(i) ;
    fila.clear() ;

    return true ;

}

int find_aux(int x)
{
    if( x == pai_aux[x] ) return x ;
    return pai_aux[x] = find_aux( pai_aux[x] ) ;
}
inline void join_aux(int a, int b)
{
    a = find_aux(a) ;
    b = find_aux(b) ;

    if( rand() % 2 ) swap(a,b) ;

    pai_aux[a] = b ;

}

int main()
{
    scanf("%d%d", &N , &T ) ;
    lp(i,1,N+1)
    {
        scanf("%d%d", &X[i] , &Y[i]) ;
        mp.insert( mk( mk( X[i] , Y[i] ) , i ) ) ;
        is_full[i] = true ;
        vet[i] = pai_aux[i] = i ;
    }

    idx = N ;

    lp(i,1,N+1)
    {
        for(int j = 0 ; j < 8 ; j++ )
        {

            int nx = dx[j] + X[i] ;
            int ny = dy[j] + Y[i] ;

            if( mp.find( mk(nx,ny) ) == mp.end() ) mp.insert( mk( mk(nx,ny) , ++idx ) ) ;

            if( is_full[ get_code(nx,ny) ] ) join_aux( i , get_code(nx,ny) ) ;

        }
    }

    lp(i,2,N+1)
        if( find_aux(i) != find_aux(1) ) {  printf("NO\n") ; return 0 ; }

    for(auto p : mp )
    {
        X[p.ss] = p.ff.ff ;
        Y[p.ss] = p.ff.ss ;
        pai[ p.ss ] = p.ss ;
        componente[p.ss].pb( p.ss ) ;

        for(int j = 0 , nx , ny , c ; j < 8 ; j++ )
        {

            nx = p.ff.ff + dx[j] ;
            ny = p.ff.ss + dy[j] ;
            c = get_code(nx,ny) ;

            adj[p.ss].pb(c) ;

            nx = p.ff.ff + dx_cyclic[j] ;
            ny = p.ff.ss + dy_cyclic[j] ;
            c = get_code(nx,ny) ;

            adj_cyclic[p.ss].pb( c ) ;

        }

    }

    int id = -1 , mn = inf ;

    for(auto p : mp )
        if( p.ff.ff < mn ) mn = p.ff.ff , id = p.ss ;
    reachable[id] = true ;

    for(auto p : mp )
    {

        if( is_full[p.ss] ) continue ;

        lp(i,0,4)
            if( adj[p.ss][i] != 0 && !is_full[ adj[p.ss][i] ] )
                join( p.ss , adj[p.ss][i] , false ) ;

    }


    lp(i,1,N+1)
        if( check(i) )
        {
            s.insert(i) ;
            checked[i] = true ;
        }

    while( s.size() > 0 )
    {
        it = prev( s.end() ) ;

        int best_id = *it ;
        s.erase(it) ;

        ans.pb( best_id ) ;
        is_full[best_id] = false ;

        for(int i = 0 , nx , ny ,c ; i < 4 ; i++ )
        {
            nx = dx[i] + X[best_id] ;
            ny = dy[i] + Y[ best_id ] ;
            c = get_code( nx,ny ) ;

            if( is_full[c] ) continue ;

            join( c , best_id, true ) ;

        }

        to_change( best_id ) ;

        for(int i : fila ) to_change(i) ;

    }

    printf("YES\n") ;
    reverse(all(ans)) ;
    for(int i : ans ) printf("%d\n" , i ) ;

}

Compilation message (stderr)

skyscrapers.cpp: In function 'bool identify_articulation(int)':
skyscrapers.cpp:85:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 1 ; i < group.size() ; i++ )
                     ~~^~~~~~~~~~~~~~
skyscrapers.cpp: In function 'int main()':
skyscrapers.cpp:180:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &N , &T ) ;
     ~~~~~^~~~~~~~~~~~~~~~~~
skyscrapers.cpp:183:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &X[i] , &Y[i]) ;
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 14 / 14
• Subtask 3: 12 / 12
• Subtask 4: 17 / 17
• Subtask 5: 0 / 20
• Subtask 6: 10 / 10
• Subtask 7: 0 / 19