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답안 #472527

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
472527 2021-09-13T17:04:20 Z CaroLinda 3D Histogram (COCI20_histogram) C++14
20 / 110
 2500 ms 64008 KB 
#include <bits/stdc++.h>
 
#define sz(x) (int)(x.size())
#define debug 
#define ll long long
#define all(x) x.begin(),x.end()
 
const int MAXN = 2e5+10 ;
 
using namespace std ;
 
struct Point
{
 
    ll x , y ;
 
    Point(ll x=0, ll y=0):x(x), y(y) {}
    
    Point operator - (Point other) const { return Point(x-other.x, y-other.y) ; } 
    ll operator % (Point other) const { return x*other.y - y*other.x ; }
    ll operator *(Point other) const { return x*other.x + y*other.y ; }
    void print() { printf("%lld %lld\n" , x , y) ; }
    void read() { scanf("%lld %lld", &x, &y) ; }
    bool operator < ( Point other ) const { return make_pair(x,y )< make_pair(other.x, other.y) ; }
    int quadrant()
    {
        if(y >= 0 && x > 0) return 1 ;
        if( y > 0 && x <= 0 ) return 2 ;
        if( y <= 0 && x < 0 ) return 3 ;
        if( y < 0 && x <= 0 ) return 4 ;
        return 5 ; //origin
    }
} ;
 
int N ;
ll ans ; 
ll A[MAXN] , B[MAXN] , G[MAXN] , F[MAXN] ;
Point p[MAXN] ;
vector<Point> cht[MAXN*4] ;
int ptr[MAXN*4] ;
 
void build(int pos, int l, int r)
{
	cht[pos].clear() ;
	ptr[pos] = -1 ;
	
	if(r-l+1 <= 3 )
	{
		for(int i = l ; i <= r ; i++ ) cht[pos].push_back(p[i]) ;
		if(l == r ) return ;
		build(pos<<1 , l, (l+r)>>1 ) ;
		build(pos<<1|1 , (l+r+2)>>1 , r ) ;
		return ;
	}
	
	vector<Point> v ;
	for(int i = l ; i <= r ; i++ ) v.push_back(p[i]) ;
	
    if(sz(v) < 3) 
    {
    	cht[pos] = v ;
    	build(pos<<1 , l, (l+r)>>1 ) ;
		build(pos<<1|1 , (l+r+2)>>1 , r ) ;
		return ;
	}

    vector<Point> convex ;
    sort(all(v)) ;

    for(int i = 1 ; i >= -1 ; i -= 2 )
    {
        int z = sz(convex) ;
        for(auto j : v )
        {
            int zz = sz(convex) ;

            while( zz - 2 >= z &&  (convex[zz-1] - convex[zz-2]) % (j - convex[zz-2] ) <= 0 )
                convex.pop_back() , zz-- ;

            convex.emplace_back(j) ;

        }

        convex.pop_back() ;
        reverse(all(v)) ;

    }

    cht[pos] = v ;
	
	build(pos<<1 , l, (l+r)>>1 ) ;
	build(pos<<1|1 , (l+r+2)>>1 , r ) ;
	
}
 
void getAnswer(int pos, int l, int r, int beg, int en, Point px )
{
	if(l > en || r < beg ) return ;
	if( !(beg <= l && r <= en) )
	{
		getAnswer(pos<<1 , l, (l+r)>>1 , beg, en , px ) ;
		getAnswer( pos<<1|1 , (l+r+2)>>1 , r, beg, en , px ) ;
		return ;
	}
	if(cht[pos].empty()) return ;
	
	
	if( ptr[pos] == -1 || sz(cht[pos]) <= 3 || px.x == 0 || true )
	{
		ll cur = px*cht[pos][0] ;
		ptr[pos] = 0 ;
		for(int i = 1 ; i < sz(cht[pos]) ; i++ )
		{
			ll temp = px*cht[pos][i] ;
			if(temp <= cur) continue ;
			cur = temp ;
			ptr[pos] = i ;
		}
		ans = max(ans, cur) ;
		return ;
	}
	
	int tam = sz(cht[pos]) ;
	while( px*cht[pos][ (ptr[pos]-1+tam)%tam ] > px*cht[pos][ptr[pos]] )
	{
		ptr[pos]-- ;
		if(ptr[pos] == -1 ) ptr[pos] += tam ;
	}
	
	ans = max(ans, px*cht[pos][ptr[pos]] ) ;
	
}
 
void solve(int l, int r)
{
	if(l == r )
	{
		ans = max(ans, A[l]*B[l]) ;
		return ;
	}
	
	int mid = (l+r+1)>>1 ;
	
	F[mid-1] = A[mid-1] ;
	G[mid-1] = B[mid-1] ;
	for(int i = mid-2 ; i >= l ; i-- )
	{
		F[i] = min(F[i+1] , A[i] ) ;
		G[i] = min(G[i+1] , B[i] ) ;
	}
	
	F[mid] = A[mid] ;
	G[mid] = B[mid] ;
	for(int i = mid+1 ; i <= r ; i++ ) 
	{
		F[i] = min( F[i-1] , A[i] ) ;
		G[i] = min(G[i-1],B[i]) ;
	}
	for(int i = mid ; i <= r ; i++ ) p[i] = Point( G[i] , G[i]*(ll)i ) ;
	
	build(1,mid, r) ; 
	
	//Convex hull part
	int ptrF = mid , ptrG = mid ;
	for(int i = mid-1 ; i >= l ; i-- )
	{		
		while( ptrF <= r && F[ptrF] >= F[i] ) ptrF++ ;
		while( ptrG <= r && G[ptrG] > G[i] ) ptrG++ ;
		
		getAnswer( 1 , mid , r , ptrG, ptrF-1 , Point(F[i]*(1-i) , F[i] ) ) ;
		
		while( ptrG <= r && G[ptrG] >= G[i] ) ptrG++ ;
		ans = max(ans, F[i]*G[i]*( min(ptrF, ptrG) - i ) ) ;		
	}
	
	solve(l,mid-1) ;
	solve(mid, r) ;
}
 
int main()
{
	scanf("%d", &N ) ;
	for(int i = 1 ; i <= N ; i++ ) scanf("%lld %lld", &A[i], &B[i] ) ;
	
	solve(1,N) ;
	reverse(A+1, A+1+N) ;
	reverse(B+1, B+1+N ) ;
	solve(1,N) ;
	
	printf("%lld\n" , ans ) ;
	
}

Compilation message

histogram.cpp: In function 'int main()':
histogram.cpp:182:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  182 |  scanf("%d", &N ) ;
      |  ~~~~~^~~~~~~~~~~
histogram.cpp:183:38: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  183 |  for(int i = 1 ; i <= N ; i++ ) scanf("%lld %lld", &A[i], &B[i] ) ;
      |                                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 22444 KB Output is correct
2 Correct 20 ms 22512 KB Output is correct
3 Correct 23 ms 22468 KB Output is correct
4 Correct 25 ms 22476 KB Output is correct
5 Correct 23 ms 22528 KB Output is correct
6 Correct 21 ms 22476 KB Output is correct
7 Correct 21 ms 22528 KB Output is correct
8 Correct 18 ms 22476 KB Output is correct
9 Correct 19 ms 22548 KB Output is correct
10 Correct 22 ms 22560 KB Output is correct
11 Correct 12 ms 22264 KB Output is correct
12 Correct 18 ms 22552 KB Output is correct

Subtask #2
0 / 90.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 22444 KB Output is correct
2 Correct 20 ms 22512 KB Output is correct
3 Correct 23 ms 22468 KB Output is correct
4 Correct 25 ms 22476 KB Output is correct
5 Correct 23 ms 22528 KB Output is correct
6 Correct 21 ms 22476 KB Output is correct
7 Correct 21 ms 22528 KB Output is correct
8 Correct 18 ms 22476 KB Output is correct
9 Correct 19 ms 22548 KB Output is correct
10 Correct 22 ms 22560 KB Output is correct
11 Correct 12 ms 22264 KB Output is correct
12 Correct 18 ms 22552 KB Output is correct
13 Execution timed out 2581 ms 64008 KB Time limit exceeded
14 Halted 0 ms 0 KB -